Rationale and method for creating lab groups that consist of four students, each from a different performance quartile
Paperwork Reduction
Most teachers don’t want to painstakingly grade every lab report from every student in each physics (or any science) class. Students within a lab group tend to produce highly similar lab reports, anyway. You really don’t need to look at more than one lab report from each lab group.
Limited Engagement?
Each student should be fully engaged in the lab activity and feel invested in writing his or her own report. So don’t allow each group to produce one report to be turned in. Each student needs to be responsible for completing his or her own report.
No Group Member Left Behind
Pick up one report from each group. But do so only when the activity is over and all the reports are complete. Let the students know which group member is to turn in the lab no sooner than the time at which the report is to be turned in. Brighter, faster students cannot race ahead of slower students since it may well be one of the slower students whose report will be graded.
No Cliques
Students naturally prefer to sit with their friends. This doesn’t always yield the best results. As the grown-up in the room responsible for the instructional program, you have the freedom (if not the obligation) to improve the environment. Here’s how you can create lab groups consisting of students from across the performance spectrum within the class.
I clearly wanted to turn assessments (summative assessments, mind you) into learning tools, as evidenced by Test Correction Journals (see previous post). But I wanted to do it differently in my AP Physics classes. Some students in AP Physics 2 had been in Physics, so TCJs were old hat to them.
So I developed Test Correction Mastermind for my AP students. The broad goals are the same: get students talking to each other about test items with the possibility of some sugar (points) at the other end if they got the questions sorted.
As was the case for TCJs, this activity is done well after the test has been administered in class and the make-up window has closed. This time, I give each lab group (3 or 4 students) a blank BairdTron and a copy of the test. Again there are 4 forms and I give different groups different forms. The questions are all the same, but scrambled differently. Different forms in adjacent groups minimizes the value of conversations overheard between neighboring groups.
The objective is to complete the test as if it were a group activity. But each group is in competition with all the other groups to get the top score (20 multiple choice items on the AP unit tests, and one free response—the free response isn't part of the TCM).
The reward structure is as follows: each member of the group gets a point for every correct answer above 15 (P=score–15). The top-scoring team members get 4 more points on top of that; second place folks each get 2. At most, a student could add 9 points to their test score. Among AP students in whom competitiveness is sometimes strongly expressed, 9 points is plenty.
When about 20 minutes of class time remain (57-minute periods), I rattle my thunder drum and announce the "The oracle is now open for 5 minutes!" Group members submit their BairdTron for scoring and return to their group. I tally up the number of incorrect answers, write that number on their form, and call them back to retrieve the scored document.
I do not indicate which items are incorrect, only the total number of items they answered incorrectly.
Assessments: quizzes, tests, exams. There is a big part of the teacher's soul that hates these things. We love our subject matter and love sharing it with our students. We love it when our students are engaged with our subject matter and learning.
Tests? What a chore. You need to construct them. You need to administer them, You need to grade them. Yuck. Yuck. And yuck.
Construction: what should be assessed and how? Is that question too hard or too easy? Administration: to what extent can cheating be prevented and how much energy is that going to cost? Grading: do you hate multiple choice or do you hate hours upon hours of grading?
To students, assessments may seem like nothing other than punishment.
Of late, there has been much examination of grading. Anything smacking of "traditional" is guaranteed to be on blast in Teacher Twitter. Some teachers have gone all in on Standards Based Grading and are eager to evangelize that movement. Others are all for ungrading, and are keen to share The Good News about that with anyone who will listen.
Having given my first assessments in 1986, I grant myself a modicum of "old curmudgeon" license. I don't recall much talk about SBG or ungrading on Twitter back then, mostly because there was no Twitter. Web 1.0 was still in the future (it exploded in 1995). If it was talked about at the conferences (national or local AAPT), those conversations eluded me. Should I have jumped on the SBG or ungrading bandwagons as soon as I heard from proponents? Maybe. My own district was pushing Myron Dueck's Learning Targets hard.
My aversion to going with anything that I deem to be trending may well be a character flaw, and I own it. I was very late to listening to anything by Norah Jones because her album was plastered all over the record stores. (Remember record stores? Yes, I'm that old.) If she was that popular, she wasn't for me. I figured it out eventually.
In any case, here's what I did with Physics unit tests in the vacuum of my own classroom kingdom.
Encore Post: Originally published February 21, 2020—in the last days of The Before Times. Sigh.
UPDATE 2/23/20: Extant course chart added.
We plan to launch our Physics of the Universe (POTU) course in 2021-22. Physics of the Universe is the physics portion of the three-course model for Next Generation Science Standards (NGSS) implementation. California is where I live and work; Rio Americano High School is where I've taught physics since 1986.
Our plan is to discontinue Physics as it has existed at the school since its inception in the 1960s, and replace it with POTU. We will continue to offer AP Physics 1 and AP Physics 2 (when demand exists). I plan to retire at the end of the 2022-23 school year, so the course will evolve considerably after I'm gone.
Here is a pie-chart representation of the course as it exists, in terms of the unit topics.
But August of 2021 is coming, so there is a course to create. The POTU Evolution blog posts will chronicle my development process for the benefit of both of my blog readers.
As this course-development project began, my first step was two turn those six segments into twelve units. And I felt I needed to move the nuclear unit. So already, some entropy is working its way into the pie chart. Notice that where I broke one segment into two or three, I maintained color fidelity to the framework's six segments.
As I read deeper into the framework, it became clear that some subsegments were more equal than others. As I began mapping out a day-to-day schedule, my concept of the course took this shape. It's not even trying to appear appealing anymore. But that's not what's important. There are 180 days to plan, and they're not going to plan themselves.
That's probably enough on the planning for now. I'll post unit schedules as I develop them. It's hard to overemphasize how drafty these visions are right now. But they are preliminary drafts at best.
A few additional details: the principal would like our POTU course to be accessible to freshmen. Given that our district is all-in on Integrated Math, any algebra necessary in the course will need to be taught in the course.
We will be adopting textbooks next year for all science courses. Our last adoption in physics was in 2008. POTU textbooks are... largely still in development. I think Conceptual Physical Science would work nicely for NGSS 3-course Physics and Chemistry, but we'll see what the adoption options are in 2020-21.
Thoughts? Ideas? Advice? That's what the comments section is for. I'm keen to hear about what you're doing as NGSS and new assessments appraoch.
Welcome to my debut Blog of Phyz post! I was encouraged by Dean Baird to write a bit about my current flexible hybrid learning plan for the 2020-2021 school year that I posted on Twitter. Great idea! I hope that it can be helpful to others as they try to plan in the face of uncertainty.
The Plan
Let's cut to the chase. Here is the outline for my plan. The rationale follows.
It is currently based on my typical pre-COVID schedule, where I teach a class two 105 minute blocks and one 50 minute class per week. It's likely that I will have to change the times, but I think the philosophy behind it is solid and adaptable.
Guiding Principles
There were three guiding principles in making this schedule: simplicity, consistency, and flexibility. Simplicity. This structure allows me to make good use of many of the high-quality resources that already exist, such as TIPERS, Ranking Tasks, Flipping Physics videos, Interactive Lecture Demonstrations, and so on. Consistency. The students will see the same general structure each week, and they will know what to expect if they have to miss class. There should never be any surprises. Hopefully this reduces the "Hey, Mr. Milliano! Did I miss anything? What did I miss?" type questions. They'll know to check the recorded videos and their independent module for the week. Flexibility. Much of this plan is structured around helping students to self-study and manage their own time. Even if we start the school year in-person, I have a suspicion that we will be online at some point. Students will need to know how to self-study, so we should explicitly prepare them for that while we're together. The teacher-led parts of the plan are things that I'd likely be able to do over video or Zoom, allowing them to work for in-person or online classes.
Independent Modules
Each module would be one week long, starting on Wednesday and ending the following Tuesday. A module would consist of seven 30-minute tasks, three to be completed in class and four to be completed at home. This could be adjusted to five 30-minute tasks and one 60-minute task, or so on.
These modules would each include at least one of each of the following.
An information transfer task. This will often be a student-choice between reading the textbook or watching Flipping Physics videos. For accountability, I will likely have students post pictures of their notes and respond to discussion board prompts in our LMS.
Sense-making tasks. These will include traditional problems, non-traditional problems, making Flipgrid videos explaining a simulation, Google Meets with classmates to collaborate and discuss ideas, posting on discussion boards, writing activities, and more.
Students will be asked to plan their own schedule, with guidance from me and the help of a graphic organizer that I'll make. As an incentive to stick to the plan and as an accountability measure, I'll check in with each student during their independent work time and see if they've stuck to their plan. If so, I'll give them a stamp or a sticker. (I'll never cease to be amazed at how motivating stamps and stickers are to 15-18 year-old students.)
Assessment
The grade will be almost entirely based on weekly quizzes, except for the occasional lab report. This means no long unit tests (to take or to grade)! I will use a version of the 10-8-6-5 flavor of Standards-Based Grading described by Kelly O'Shea on her blog.
The weekly quiz can assess any standard from throughout the whole year, and most standards will be assessed multiple times in class. The most recent standard grade will always replace an older one. Yes, even if it's worse. (Although that rarely happens.)
Student-initiated individual reassessment
Students will have the option to reassess any standard they want throughout the whole year, assuming they have put in the work to understand it better than they did previously. I will have several policies in place to make sure that these reassessments are (a) genuinely reflective for the student and (b) not an administrative nightmare for me.
Reassessments will be taken on Fridays in class during the typical self-study time. This gives me a specific time to focus on this reassessments, rather than try to do them in random spurts throughout the week.
The student must sign up to take a reassessment by the Tuesday of the week they want to reassess. This tells me that the student has put thought into what they want to reassess.
When signing up, the student must provide concrete evidence that they have done extra practice on that standard. This tells me that they have learned from their past mistakes and have put in the work to refine their thinking.
The student can only reassess two standards per week, and they must be from the same unit. This helps me write new assessments or find questions quickly and easily.
I will only write reassessments for two units and four standards per week. This means I'm not trying to write too many new assessments per week.
Only x number of students per class can reassess in a given week. I don't know what the optimal number for x is, but I know there needs to be a limit.
There is a definite final date to reassess. For me, that's Friday, December 4, 2020 for the first semester.
Why I like this plan
This plan provides flexibility. There is so much uncertainty surrounding school plans for next fall, and we all know anything could change at the drop of a hat. I believe that this structure could provide the flexibility needed to work fully in-person, fully online, or in a hybrid model. It also allows me to do both online and face-to-face with roughly the same lesson plan.
This plan is not complete. I teach in a St. Louis county school, and all county districts have agreed to release their plans together on July 20. So I don't really know what my schedule will look like yet. With this structure, though, I am confident that I can start working on building some independent study modules.
Some acknowledgements
This plan has been heavily influenced by several conversations that I've had recently with physics teachers on Twitter. I'd like to thank Wesley Morgan for encouraging me to keep things simple this year, Frank Noschese for talking about his plan to make one plan that works in any scenario, and Phillip Easton for sharing how his class has been structured in a similar way in the past.
When the pandemic closed schools in mid-March, one of the myriad question marks that loomed was if or how the Advance Placement Exams would proceed. As it became clear that schools would not reconvene for the remainder of the year, that question mark loomed larger. I teach AP Physics 1 and AP Physics 2.
The College Board decided to proceed with the exams, albeit in a highly modified format. Exam content was pruned. College Board offered online lessons intended to prepare students for the content and format of the exams.
From what I gathered via Twitter, most instructors jumped on board on did what they could to coach their students for the exam via distance instruction. From what I could tell, there was considerable highly admirable and herculean distance learning being implemented in the AP Physics realm.
I chose a different path. It was never clear to me that many of my students were aiming to take the exam. At my school, students are free to enroll in AP courses without being required to purchase the exam. Survey results of whether students were going to take the exam in light of the pandemic, most of my students chose neither "yes" nor "no". They chose "maybe".
In AP Physics 1, I continued teaching the course content: Waves, Electricity, and Circuits.
It seemed wrong to allow AP Physics 1 students to be allowed to go out into the world not knowing what waves were.
So I puttered along with my non-onerous, asynchronous lessons delivered and collected via Google Classroom, making my way through waves, then electrostatics, and electric circuits.
What about my students who intended to take the exam? I instructed them to join the College Board's online course webinars. I unlocked the practice items available to them in AP Classroom.
The point is that all of us who teach the College Board's Advanced Placement had to make a choice of what to prioritize: exam preparation or course content.
I chose course content. From what I could glean, I was alone in this choice. That didn't bother me. I didn't blog about it then because I wasn't looking to win converts or initiate a spirited debate. I trusted everyone to make the choice best suited to their situation.
The presumption of the College Board was clearly that we would jump on board with exam prep in these challenging times. From what I could tell from their communications, The Exam wasn't everything, it was The Only Thing.
In a normal, face-to-face year, I would have completed those topics prior to the exam and would have ended the year (post-exam) with what I call "Light Desserts". That unit covers plane mirrors, prisms, rainbows, double rainbows across the sky, mirages, why the sky is blue, and polarization. Not this year.
In AP Physics 2, I had completed virtually all principal instruction. We were ready to go into exam prep mode, for the Exam That Was. I directed AP2 students intent on taking the exam to join the College Board's webinars, too. And assigned the others a few enrichment activities.
It is not clear that my choice "has made all the difference", but it was the choice that I made. And it still seems like it was the right choice for me and my students.
Howdy all, First, I'd like to thank my friend and colleague, Dean Baird, for inviting me to be a guest blogger here at The Blog of Phyz. Briefly, I've been teaching high school and college-level physics since 1998, and in that time I've seen a lot—but nothing like what we're all dealing with now. In addition to my teaching duties, I am the secretary and webmaster of Physics Northwest (group of physics teachers in the suburbs north and west of Chicago), and we've worked with our own teacher network as well as the TAP-L email list to assemble a long list of available online resources for teaching physics. This list of information has been posted to the front page of the Physics Northwest website at https://sites.google.com/site/physicsnorthwest/ Update 3/28/20: Here's a new and improved Google Sheet version of Matt's collection that we've been working on: Physics Distance Learning Resources. Consider it Version 1.0, and load us up with links we missed down in the comments. Remember: Google Sheets can have tabs. This sheet has four tabs (so far). Check them all out. I apologize that the list isn't formatted and organized yet, as I've been busy tackling my own struggles with online teaching this past week, but now that I'm on spring break I'll have some time to tweak the list (so stay tuned). Any suggestions for additions and/or edits are welcome. Take care, folks. It's a rough time for the lot of us, but in times like this I like to remind myself of the old Marine Corps motto: Improvise, Adapt, Overcome. Cheers - Matt Lowry [Matt has been my presentation partner for "Skepticism in the Classroom" workshops at AAPT and NSTA Meetings. To see our first collaboration, check this out!And if you click the Physics Northwest link above, you will see a collection of great physics teachers, some of whom you may know from Twitter or elsewhere. Matt's in the fourth quadrant in the fashionable "Keep Calm" T. –Dean]
might be different from yours. And chances are, yours will be more robust than mine.
The physics instructor (and high school instructor) social media sphere is rife with tales of how best to lead online courses complete with live video lectures. A tidal wave of software tool recommendations have flooded in. Solutions that were previously subscription-based are suddenly free. Industrious instructors are assembling indexes of quality resources. Online instructional veterans are posting pro tips for the flood of novices.
All of this is appropriate, natural, and good. And I am completely overwhelmed.
Whatever path colleagues take into the uncharted waters of this coronavirus transmission break is correct as far as I am concerned. There is no One True Path for this. Different districts have communicated different expectations. Different teachers have different students and different temperaments and different resources and different abilities. One size cannot fit all.
My district has directed instructors to make themselves available to students via virtual office hours from 8:30-10:30am and 12:30-2:30pm each school day. No new assignments are to be given. No student work is to be graded. I am in a suburban unified school district (about 38,000 students at 50 sites). The district is not 1:1 (one computer for each student). We were duly warned that giving assignments or grading work online would likely constitute a violation of the Individuals with Disabilities Education Act.
In the face of my trepidation, I pulled back for a little perspective.
When we left school last Friday, this break was going to be shockingly long: no classes for a month. Administrators would continue to report to their respective sites in the interim. Classroom access would be allowed for instructors (6am-6pm). Less than a week later, our sites are now abandoned shut—alarms are armed 24/7. Counties are on shelter-in-place or full lockdown. The governor does not foresee schools reopening this academic year. This is objectively a full stop.
Students have been thrown into an unprecedented spiral of lost activities (sports and other extracurriculars, prom, graduation). Their parents may be newly unemployed. Families with lost incomes wondering how they will obtain groceries amid the hoarding. They may have loved ones suffering from COVID-19, and they should be doing what they can to avoid being a vector for the contagion.
So how pressing is the physics curriculum to my students? Answers will vary. But I think it's safe to presume that it's less than it was a week ago. Substantially less.
What to do? I don't know. Here's what I've settled on.
I already have a decent "static" online physics curriculum presence at phyz.org. Much to read, many worksheets to do. Students do have their textbooks. And the Internet bursts with resources. I am going to encourage my students to learn the remainder of the year's curriculum. To learn it as if they were going to have their final exam at the end of the school year. My final exams focus on the big, important ideas that should be internalized by the end of the semester.
As is always the case, learning physics is a conscious choice. Some students choose to learn physics without ever having enrolled in the course. Many students enroll in the course but never choose to learn physics. It has always been thus.
I will be in contact with my students through the school's SIS mass email feature to provide direction for how they can engage in learning. We will not have all the labs, activities, and demonstrations that face-to-face classroom instruction would afford. The learning may not be as robust. But the big ideas and fundamental principles should get through.
So that's my path. Providing some resources and guidance, with the student goal of being able to perform well on the semester final exam. With that vision, I feel like I can move forward.
But the High School Adaptations followed a different path. They were available for purchase for years (VHS and then DVD) from Intelecom. But any and all distribution ceased years ago, and these pared down and reworked videos seem to have been lost to the mists of history. You cannot buy them and you cannot stream them.
So I decided to post them as "unlisted" videos on my YouTube channel. Two copyright claims popped up when I uploaded them. In "Introduction to Waves," someone owns the license to The Marriage of Figaro music that plays in the episode, so that episode is subject to ads that would benefit the license holder. In "Navigating in Space," a minute or so of Voyager Grand Tour animation is owned by the BBC. Inclusion of that minute would block the video from running, so I removed the offending content and tried again. No block; no strike!
And now that they stream, they make for nice YouTube homework assignments! This frees up classroom time for other activities.
I feel awkward posting these videos since they don't really belong to me. I have not been asked by any license-holding stakeholder to cease or desist. At this point, they may be covered by Fair Use. I honestly don't know. It is certainly not my intent to infringe on anyone's copyright.
With the NGSS-based California Science Test (CAST) set for its maiden administration this spring, a reference sheet has been prepared. Students have access to the reference sheet while they take the exam. Here's the reference sheet.
Reference sheet development can awaken passions that physics instructors didn't know they harbored. So let's go through it. (It might be helpful to print the sheet or have it open on another screen. Blood pressure medication? A preemptive dose might save a life here.)
FORCES AND ENERGY Good: Newton's Second Law, the weight equation, universal gravitation, Coulomb's law, gravitational potential energy, kinetic energy, work-energy theorem. All good.
Meh: Using w for weight. A little bit non-standard, but the judges will allow it.
MOTION Good: F∆t = m∆v, the use of ∆v in the equation for acceleration: the ∆ is critical here.
Meh: The use of ∆t rather than t. We never create problems involving isolated clock readings (t); intervals (∆t) are always given. The ∆ in front of the x in the equation for speed? I can take it or leave it.
Meh: The use of J for momentum. That's a rare one. I've seen it, but it is not common. I prefer ∆p, and I don't think I'm alone.
Bad: s for speed. I am reminded of a line from Star Trek: "A Vulcan would not cry out so." In this case, I will turn that phrase to "A physics teacher would never, ever use s to denote speed. Ever." I hope I'm not being ambiguous here. The very use of s for speed makes me wonder if anyone associated with physics instruction was involved in developing this reference sheet. A math teacher might make such a miscue, but not a physics teacher.
Wha?: Using the Greek letter, rho (ρ), for momentum. Why? Lowercase ρ is a symbol used to represent density in high school or college courses. It is also used to represent resistivity. Nobody ever uses ρ to represent momentum. Anywhere, ever! Momentum is represented with the letter p. Extra effort is required to insert the letter ρ. I am dumbfounded.
KEPLER'S LAWS
These are here for the benefit of items addressing Earth Science PE, HS-ESS1-4. I'll let them "Meh" or "Wha?" the notion that e = f/d is among Kepler's Laws.
WAVES Good: The wave equation and the Planck-Einstein relation. I would have put them in that order, but okay.
Wha?: The reference sheet is set in a sans serif font. In high school, we use lowercase f for frequency. Someone at CAASPP seems to have found the special character, ƒ, which bears a striking resemblance to an italicized, lowercase f. If a pianist sees two of those in a row (ƒƒ), they'll hit the keys hard. The symbol, itself, is called "F with hook," or "florin symbol" and is used to denote the Dutch guilder, for example. This has been Sheldon Cooper's "Fun with Fonts" with your host, Sheldon Cooper.
EXPERIMENTAL DESIGN
Mostly good. It it's me, I'd use a cross (×) rather than a bullet (•) to indicate multiplication. The bullet really isn't a multiplication symbol. The dot (·) is, but the cross is more appropriate here.
At the risk of belaboring a point made in the post critiquing the practice items, I will point out to our gentle readers that no reference to index of refraction appears on the reference sheet. No n = c/v and (thankfully) no Snell's law. Recall that one of the practice items expected students to be familiar with the meaning of index of refraction.
CONSTANTS
If someone at CAASPP sees this, please explore the use of the dot symbol ·. On my Mac, I hold down the shift and option keys while typing a 9. It's more professional than the big bullet • that you get with option+8. And drop the spaces in unit configurations.
I see N·m as better than N • m for newton-meters.
In all, the reference sheet is more good than meh, bad, or wha? But I wouldn't be keen to print it up and have students use it throughout the year. Replace the speed s with a v and the momentum rho with a p, and I can live with the remaining quirks.
The California Department of Education's California Assessment of Student Performance and Progress program has released a set of High School Practice Items in connection to the state-mandated exams to be administered this spring.
As detailed in a previous post, six of the 50 released items relate to high school physics topics. Sixteen are from Life Science, 15 from Earth Science, 9 from chemistry, and 4 from Engineering Design.
Remember: chemistry and physics topics have been combined into the more omnibus "Physical Science" realm of the high school science Performance Expectations (PEs). While NGSS's HS-PS1: Matter and Its Interactions is predominantly chemistry, HS-PS2 Motion and Stability: Forces and Interactions, HS-PS3 Energy, and HS-PS4 Waves and Their Applications in Technologies for Information Transfer are predominantly physics PEs.
Nevertheless, 9 of the 15 released HS-PS items assessed HS-PS1 while 6 were shared among PS2, PS3, and PS4. If there is a blueprint available for the composition of the operational exam, I am not aware of it. So the Practice Items may or may not reflect the mix of the operational exams.
UPDATE: I found the blueprint: for the high school test, see page 8 of the CAST Blueprint. Not surprisingly, it appears the operational exam will include physics items in greater proportion than in the released practice items.
Let's take a look at those six. I will state each item's Item-Level Claim Statement (ILCS). Click the ILCS to see the actual item. My analysis will follow each ILCS.
Identify the relationship between mass and acceleration. [Click to see item.]
In general, the item is perfectly reasonable. It speaks to the interpretation of graphed data obtained through a laboratory activity that might be done in a high school setting. The item links solidly with the corresponding PE (HS-PS2-1: Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.).
But there is a problem. And I say this as someone who had the privilege of sifting through many, many potential exam items offered by ETS for use in state-mandated testing from 2003 to 2013. The problem is the title of the graph.
The graph on this item is correctly constructed as Acceleration vs. Mass: experimenters would have measured the acceleration of a cart while varying the cart's mass. But the graph is titled Mass vs. Acceleration. I have to assume this was an oversight on the part of ETS and anyone (if there was anyone) tasked with content review.
Some might object that the mathematics is simplified too much in this item. It does leave open the question of how deep the arithmetic might go in operational items. If you make this question about a neutron and a deuteron combining to form a triton, the principle is same, but the numbers are more formidable.
In the event that anyone tries to champion the new assessments as ground-breakingly novel, consider this released test question from the old Academic Content Standards era: Conservation of Momentum RTQ. In fairness, the new one does have color. And kilograms, rather than tons!
But this brings up an ongoing problem suffered by standards exam item-writers. Standards (now PEs) are often important-sounding principles that turn out to be difficult to write a variety of items for.
Select the design solution that best meets the provided criteria about momentum and force during a collision.
This item reveals the challenges associated with writing questions for PEs like HS-PS2-3: Apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision. The item has a very long stem leading to the answer choices. And the choices are quite word-heavy, too.
Students with a firm grasp of the fact that increasing impact time reduces impact force will find their way to the correct answer. The item will make them work for it, though. I'm not faulting anyone here: awkwardness is in the nature of writing items aligned to standards (PEs) like this.
It is linked to HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
Might it connect more directly to HS-PS3-2: Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects)? The clarifications on PS3-2 say "Examples of phenomena ... could include the conversion of kinetic energy to ... energy stored due to position of an object above the earth. Examples of models could include diagrams, drawings, descriptions, ...]
Aligning items to PEs is sometimes a dark art; I'm inclined to grant CAASPP latitude on this matter.
I have reason to suspect Rhett Allain will not approve of dropping a tennis ball from the top of a building and stating that air resistance is negligible. Neglecting air resistance is a simplifying step. Dropping a tennis ball might be a requirement of item-writing guidelines that prohibit scenarios that might cause significant injury. Dropping a cannon ball would inherently render air resistance more negligible, but would also present a greater potential (!) for damage if carried out in real life.
There's some contrivance at work here: Determining the kinetic energy of a dropped ball in reality would involve measuring its mass and its speed. The speed, alone, allows one to determine the height from which the ball was dropped. But the standard demands items, so here we are.
Describe how wavelength is related to the change in the medium.
The PE being addressed here is HS-PS4-1: Use mathematical representations to support a claim regarding relationships among the frequency, wavelength, and speed of waves traveling in various media. The Disciplinary Core Idea expands this to: The wavelength and frequency of a wave are related to one another by the speed of travel of the wave, which depends on the type of wave and the medium through which it is passing.
One word that doesn't appear anywhere in the HS-PS PEs is "refraction". So we have a judgment call here. Do we assess attainment of this PE by asking about what does or doesn't change at an optical boundary during the process of refraction?
Students must also know what index of refraction refers to and that greater values indicate slower transmission speed in transparent materials. I'm delighted to teach the material; no one gets through my course not knowing how rainbows work. But I might have omitted index of refraction thinking no harm would come to my students based on a strict reading of the PEs and DCIs. I would have been wrong.
There are certainly topics I am skipping based on my reading of NGSS. Which ones will show up in the assessments? Time will tell. I'm not a huge fan of surprises like this.
Minor point: Numerical values were used for the indices of refraction and for the wavelength of the laser. I'm not sure why an infrared wavelength was chosen. When I use lasers in class, I prefer to stick to visible light varieties.
I like this one because it shows a weakness in my own instruction that will require a bit of patching up.
During classroom instruction, students should be able to examine a number of systems and understand how potential energy changes within them. A rock and the Earth, two opposite charges, two like charges, magnets, springs... Students should know where potential energy is zero and where it is maximized in a given system.
I'll need to work on more explicit instruction of that beyond gravitational systems.
If you made it all the way to the end, pat yourself on the back. This was a long one. I will nourish a hope that we get more released items each year. I was unambiguous about this priority when I served on California's Assessment Review Panel. But panelist's wishes were not always accommodated. I really am trying to be subtle here! In any case, I will try to maintain cautious optimism.
Having said that, I will add that the most fun I had practicing and honing the craft of teaching physics occurred in the years when my students were not assessed with end-of-course exams intended to enforce a measure of accountability. My students in that era did not leave my course with woeful gaps in their physics knowledge. But that's just me shaking my fist at the sky.
I believe the first time Physics was offered at Rio Americano High School, it was for the 1966-67 school year. My now-retired former colleague, Marion Gribskov taught the course for 19 years until he was called upon to teach Chemistry in 1985-86. I began teaching Physics in 1986. Based on my current reading of the tea leaves, I will teach Rio's final Physics classes in 2020-21.
In 2021-22, I will begin teaching Physics of the Universe (PotU). This will be our school's adaptation to the Next Generation Science Standards and the California Science Framework's digestion of NGSS.
As with most transitions of magnitude, there will be some awkwardness. I have penciled out a roadmap that will take my school from where we are now to where we need to be in 2023.
Here's the roadmap.
Here are the accompanying notes, for what they're worth.
PotU/11-12: Physics of the Universe for Juniors and Seniors. “Algebra 1”-equivalent prerequisite. These juniors and seniors will have had the opportunity to enroll in Biology of the Living Earth and Chemistry in the Earth as freshmen and sophomores. PotU/11-12 might be a transitional course for use during Rio’s migration to the NGSS Three-Course model. It will be taught in 2021-22 and 2022-23 only. For 2023-24 and beyond, PotU will be a 9-10-level course. PotU/11-12 might be retained to accommodate juniors and seniors who did not enroll in PotU/9-10 but aren’t up to the challenge of AP Physics 1. PotU/11-12 will omit physics topics not included in the California Framework Physics of the Universe course model, and add earth science topics as needed. PotU/9-10: Physics of the Universe for Freshmen and Sophomores can omit the math prerequisite but will need to integrate some elements of algebra instruction. Concurrent offerings of PotU/11-12 and PotU/9-10 in 2021-22 and 2022-23 are to prevent classrooms populated with freshmen through seniors. We put an end to this practice with Earth Science in 2016 with the introduction of Conceptual Physics. Earth Science was restricted to freshmen and sophomores while Conceptual Physics was restricted to juniors and seniors.. Development of Rio’s Physics of the Universe courses will be undertaken during all available collaboration time in 2019-20 and 2020-21 and additional time as needed and approved. *Beginning in 2022-23, the prerequisite for AP Physics 2 will be “successful completion of AP Physics 1.” [The previous prerequisite had been “successful completion of Physics or AP Physics 1.”] **Beginning in 2023-24, PotU/11-12 will be discontinued and PotU/9-10 will be the sole non-AP Physics course.
It should be noted that my district has not adopted physics textbooks since 2008. While the district has opted for the three-course model, it doesn't seem any textbook/curriculum program exists for this new course.
It seems there is an assumption among NGSS visionaries that they have provided a grand vision, and now it's up to classroom instructors to develop the curriculum that will implement their vision. That's simply not going to happen. I'm delighted to develop curriculum... to implement my own vision of what high school physics instruction should be. Anyone else who has a vision needs to provide their corresponding curriculum if the hope for implementation.
Between now and then, things may change in terms of the process. This is version 1.0 of how I think it will all go.
The time has come for students of science in California. That's right, CDE's CAASPP's NGSS CAST from ETS goes operational this spring.
That wasn't a cat walking across my keyboard; that was the initialisms and acronyms that spell out the new state-mandated assessment regime in California.
NGSS is, of course, the Next Generation Science Standards. CAASPP is the CAlifornia Assessment of Student Performance and Progress. CAST is CAlifornia Science Test. (I'm suddenly envious of the science tests given in Missouri and Virginia, less so for those in Colorado, Delaware, Georgia, Hawaii, Maine, Nebraska, Rhode Island, Washington, Wisconsin, and lastly, Louisiana. ETA: Looks like I missed Michigan and passed Pennsylvania. I'll be here all weak.)
NGSS has been around for some time now, with its multi-colored documentation of Performance Expectations, Science and Engineering Practices, Disciplinary Core Ideas, and Crosscutting Concepts. California has digested NGSS into its own Science Framework. The Framework and NGSS articulate broad, sweeping visions of science instruction.
CAASPP is the program tasked with testing. The previous iteration of this (in California) was State Testing And Reporting (STAR). This is where the lofty visions presented in the vision documents (NGSS/Framework this time) must be broken down into test questions ("assessment items"). As it was during the STAR era, the California Department of Education (CDE) has contracted the services of Educational Testing Services (ETS) to develop the CAST. (The proliferation of initialisms and acronyms indicate the importance of the enterprise.)
Assessments are where the rubber of the grand visions meet the road of perceived accountability. I say this as someone who served on the Golden State Exam development committee and was appointed by the State Board of Education to serve on CDE's CRP (Content Review Panel, later rebranded as the ARP: Assessment Review Panel).
I am a relentless advocate for released test questions (RTQs). The vision documents are necessary, I suppose. But they never really specify measurable outcomes. The visions boil down to "all students should be knowledgeable in science and capable of performing scientific analysis and related tasks." But vision documents quickly blow up into phonebook sized documents with webs of interrelated objectives that can make tri-level chess seem simple by comparison. But with a sufficient bank of RTQs, I will know exactly what your vision was. Inductive reasoning is really the only way to connect standards and assessments, here.
Life Science: 6 - Earth Science: 1 - Physical Science: 0 - Engineering Design: 0
Remember that in NGSS, high school science opposes three domains: Life Science, Earth Science, and Physical Science. The old subjects known as "chemistry" and "physics" have been combined into Physical Science. But not even one RTQ covered anything in Physical Science.
I have been running poster-based ad campaigns to promote physics enrollment since the 1990s. (I tried personalized, direct mail prior to that, but that was troublesome and expensive.)
Previous campaigns were documented in previous blog posts: 2016 and 2012.
But after 30+ years of teaching, some things lose their novelty. Homecoming rallies. Actually, any rally. I could go on, but I digress.
I wanted to use a different campaign for Fall 2019 sign-up season. And that season is coming up soon.
Each of us has our own school community, culture, and instructional styles to work around when designing ads. I did my best to take these into account for this newly-minted campaign.
As with the previous campaigns there is a theme and variations on that theme. Some employ my own photographs. Others use found images, some more classic than others.
These may or may not work for me. Advertising is a fickle alchemy at best. You are certainly welcome to use them if you think they may work for you. Click to embiggen.
On Wednesday, The Insurance Institute for Highway Safety (IIHS) released its 2019 list of Top Safety Picks and Top Safety Picks+, it's two highest ratings for vehicle safety.
"Challenge Accepted" is the title of their report; IIHS increases the rigors required for vehicles to earn the top ratings. They keep the goalposts moving to compel manufacturers to better protect occupants each year. IIHS hopes that the 57 models that qualified for this initial list will be joined by more models as 2019 moves forward.
Years ago, Griff Jones worked with the IIHS to create the classic, Understanding Car Crashes: It's Basic Physics. It's an excellent capstone for instruction in mechanics. As mentioned in a previous post, I developed a fairly robust single-period lesson around vehicle safety and Jones' video.
It brings the physics home to the students and gets them talking about vehicles they ride in or might aspire to own. I hope the lesson plants a seed that will get them to make vehicle safety and crashworthiness a primary factor when they consider a vehicle purchase.
As a native of Michigan, I was disappointed to see only one American model listed as a Top Safety Pick. Japanese, South Korean, and German makes and models proliferate these lists. I hope US nameplates step up their game, but their track record does not nourish my hope.
Let's say you you were into making solar ovens. Let's say that you decided a few years ago to make the best solar oven ever. Further, let's stipulate that you saw a nearly meter-diameter Direct TV antenna on the side of the road. An idea happened. You rushed to the local plastics store and bought highly reflective Mylar and glued it to the antenna.
Your solar oven was pretty amazing. While the hot spot wasn't super small, it was hot. Really hot. It can pasteurize a liter of water in 15 minutes.
And now you work at the Exploratorium and you think that you might bring it to work for grins. If you forget it in the back of the your Outback face up on a sunny day near the solstice, well, it can melt the molding in a fairly impressive way. I think I was lucky that my car didn't catch on fire.
You might be wondering how I could make such a mistake? I had a lot to carry into the Exploratorium, and the mirror wouldn't fit on the cart. I planned on coming back in a few minutes, but I got busy doing something else, and it slipped my mind. Coming back in the afternoon, I sat in the driver seat and looked into the rear view mirror.
Uh oh.
If you want to make your own parabolic mirror, you can find some excellent instructions here.
Throughout the year I mentally categorized everything as either pre- or post-AP. When I finally made it to the promised land of post-AP testing I then encountered a new challenge, keeping students engaged for a few weeks when they want to do absolutely nothing. I had many options, even putting a poll to them just for information (reserving the right to completely disregard their #1 choice of "do nothing"). I could talk about topics not covered in AP C like waves or optics or thermo or relativity? We could do a research project or have some kind of demo build? They could present a talk? Some ideas seemed better than others but the timing wouldn't work.
I finally settled on doing a series of group competitions, something different each day, something hands on and fun. I found lots of ideas online, some from labs I didn't get to do, but did struggle to find ones that were Electricity & Magnetism (second semester) focused instead of Mechanics (first semester) focused. I was hoping that the competitions could be on the same topics they would later be tested on for their end-of-semester final. Unlike most AP classes, I opted not to give students a final prior to the AP test. The argument is usually that students need the practice of an AP-like exam prior to the test; so we completed mock AP exams for practice but not for a grade. My students may take up to six AP classes in their junior or senior year so they have several weeks of high stakes testing (class finals) before more high stakes testing (AP exams). I decided that the practice and their mental health was more important than their grades at that point in time and they could take the final exam during finals week.
Since I was building the competition up from scratch there was a lot of writing, re-writing, last minute tweaking and of course post notes for next time. In the end it was a workable model with no major issues but as is often the case with the first time through, it wasn't quite right. In either case now I have examples and procedures for a series of activities to either use in the same way next year or throughout the year.
Day 1: Explanation and Bridge Building
On the first day I explained to them that they would be arranged into groups and competing each day for the rest of the school year. Each group was assigned a Greek letter and asked to come up with a clever name using the letter. I tried to split Chi, Psi, Pi, etc. from being in the same class and removed Alpha to save as my example of "The Alpha Academics." As expected, my students were way more clever than I and came up with some great names: Gamma's Cookies Oof (Omicron upper and lower case) Beta Testers Mooupsilon Kappa-citor An Iota of Understanding
I introduced the format of the competition using this powerpoint. It had the rules, grading specifics and the explanation for each day's competition, which was never revealed ahead of time. I explained to students that coming up with the name for our little competition was hard, I almost decided on the Phunger Games (like the Hunger Games series) but just couldn't. It came down to the morning of when brilliance struck and I decided to name it the PhysX-Games, complete with logo based on the popular X-Games:
Students were of course very concerned about how their grades would be affected by the competition. I did not wanted to punish them if their group didn't win every day but I wanted everyone to put effort in. I also wanted them to be rewarded for working well as a team and accomplishing tasks. I opted for a system that separated individual effort from group effort. Each day that students were present they could earn 5 points for actively participating. Each group would earn points for the day for accomplishing the task but they would earn more points for being the best at it. Good participation on an individual level required helping their group for the whole period. Sleeping, doing other homework or being caught with a cell phone meant zero points for the day. These participation points went into students' lab category so it was a welcome bump for most. If a student was caught with a cell phone that day their group could not win the competition, but it did not negatively affect the other group members' individual points. I would keep a running tally of each group throughout the competition so we could always see who was in the lead.
But why care if you are "winning"? The prize had been another sticking point initially. What do I offer students who are only a few weeks from graduating, that are mentally "done" after AP testing? I hadn't offered extra credit all year so it seemed like a good reward. Specifically I decided to add enough extra credit to their individual final exam grade so as to boost their semester grade by 1%. Yet with three classes of AP Physics C I had to find a way to limit my first few periods from giving the last class the "answer" to the challenges each day. I needed a way to keep groups between classes competitive. So I upped the reward. The group with the most points in each class would get points added to their final exam to raise their grade 1% but the group with the most points across all three classes would get 2% added to their grade. This was met with hoots and hollers in my classes. I need not worry about answers being shared between classes, they were in it for a grade bump and the competition was fierce.
After the explanation and group naming we didn't have time for a long competition on the first day. Instead we started with something basic, balancing uniform sticks over a table edge. Groups were given five uniform paint stirrers and five uniform meter sticks. They were given instructions which included the rubric I would be grading them on. Without attaching the sticks in anyway to the table or counter-weighting them students were to extend each group of five out as far past the table edge as possible. Points were awarded for balancing the sticks and a bonus was given to the group with the farthest reach for paint sticks and another for the farthest reach for meter sticks. I did find that my naming it a Cantilever bridge was a bit of a misnomer; the activity is similar to the Take It From The Top activity from the Exploratorium.
Initially students tried to use some of the meter sticks as their own counterweight so we had to specify that the farthest extended meter stick had to be the top one. Students were to calculate the hypothetical Center of Mass of the system based on their measurements and assume no thickness to the sticks. The record for paint sticks was 41.4 cm and the record for meter sticks was 120 cm off the table. Groups would go back and forth, adding millimeters at a time as the record was erased and rewritten on my front board. It was a tense day in Physics!
Day 2:Mass & Spring
To review oscillations and simple harmonic motion (SHM) I adopted a lab practical challenge I had read about but unfortunately can't remember where. Students were challenged to hang the correct mass from a spring so that it's period was as close to 1 second as possible. Again their instructions included the rubric so they knew how to earn points. Students are given no other information however, and have to first determine what they need to know about the spring in order to find the needed mass. Once calculated, students would hang the mass and spring from a Vernier Dual Range Force Sensor and start it oscillating. They would use the software to determine the period for five cycles then divide by 5 to find the period for one cycle. Each class was assigned a different target, 0.5 s or 1 s or 1.5 s. I had used stiff, old springs that students had not worked with before so that they had unknown larger spring constants. This meant that the 1.5 s period required a large mass and so I changed it to 0.75 s for that class. Students used the Vernier probes to calculate the spring constant as well and so everyone got very accurate results as seen at below.
The second stage of the competition was to determine the mass of an unlabeled or hidden mass using the same procedure but in reverse. I used several old masses found in the back of my cabinet that had had their labels worn away over the years. I also made unknown masses out of toilet paper tubes and dead batteries. Each mass was measured and recorded so that I could see how close each group came. If they calculated the unknown mass to be within 10% of the actual they received group points. The group closest to the actual mass received bonus points; bonus points were also awarded for the group that got closest to the assigned period.
In the future I think I will decrease their accuracy by only providing a spring scale for the initial determination of the spring constant. This will make it harder for groups to get so close to the assigned period and award groups that employ careful lab techniques. I would still use the Vernier probe to determine the period of the oscillating mass.
Day 3: Flying Cups
Since our competition started during the second week of AP testing there were still students that were occasionally gone to take AP Exams. On those days they did not earn their individual points for participating in the PhysX games but they were also not penalized for missing them, it was excused. If they were *cough cough* "sick" that day however, they would have to complete a make-up activity. If the equipment could be easily gotten at home they could do it there but some competitions required sample data for their alternates because students did not have the equipment at home.
The Flying Cups competition however, could easily be done at home. I saw this for the first time at an elementary school Science Night and immediately decided to do it in my classroom. This video (also below) explains the how to's and the teacher flies several different models. Essentially two identical cups (made of paper or thin plastic) are taped together at the bottom. A chain of four or more rubber bands is made and wrapped around the center of the cups and held on one end. When the cup is released and the rubber band chain pulled the cup is launched forward.
Each period, 30+ AP students were completely engrossed in flying these cups. They tried all kinds of models, trying to figure out if paper or plastic worked better, a longer rubber band chain or shorter, more rubber bands or fewer, added mass at the center or the edges, etc. In the end a few smart students realized that launching from on top of a picnic bench gave them a distance advantage. Soon everyone caught on and eventually the whole class launched from a small hill in the center of our school. Some students were better launchers than others, one of the more successful being a varsity baseball pitcher. Groups earned points for each meter their cup traveled before striking the ground (not rolling) and had a bonus for the farthest in each class. By the end of the day the record was 14.7 m, with most groups over 9 meters. It was a simple activity, definitely mechanics but very fun.
Day 4: Leyden Jar
This was an activity that I used to do for years in my regular Physics and even Conceptual Physics classes. I taught students about parallel plate capacitors by having them build a simple Leyden Jar out of a film canister. I still hoard film cans to this day even though I haven't had time in the curriculum to do this for years. For the competition students were instructed to use a small film can, or a jar if they brought their own, to make a simple capacitor. This old video of mine shows the basic construction:
I had asked students to bring in cups for the flying cups activity and jars for the Leyden Jar activity without telling them what it would be for (so they didn't research it in advance). A larger jar would increase the capacitance their jar could hold, something they realized too late. Students were challenged to build a Leyden Jar that would hold a charge and then asked to hypothetically calculate what the capacitance should be using the cylindrical parallel plate equation they found in their textbook. After their calculation we charged up their Leyden Jars with my Whimhurst machine and measured the capacitance using my new capacitance meters.
I found that you have to be careful to stop charging the jar before it discharges itself, something that happened quickly for sloppily made jars. I used alligator leads to connect the Whimhurst machine (with discharge electrodes far apart) to the inner and outer surface of the jar being tested. At least one of the leads had to be removed for testing or you would measure the capacitance between the much larger Leyden Jars of the Whimhurst machine.
Students got HUGE errors between their theoretical and measured capacitance, as in the hundreds ofpercent. I need to improve the testing system if I ever want points to be awarded based on their error. Students had to research the dielectric constant of their jar, be it plastic or glass, and there is a lot of variety in that value depending on the actual material. Also without a pair of calipers students had to try to estimate the thickness of their jars as best they could. One creative group asked to borrow box cutters to cut off the thicker lip around their film can so that they could more accurately determine the thickness. Generally the smaller film cans had a higher percent error and a smaller capacitance. The large jars brought from home tended to be more accurate and their larger surface area gave them a larger capacitance. My students were able to produce capacitors from 10 (film cans) to 100 (glass mason jars) picofarads.
While I liked the review of capacitance, specifically what it was and what physical attributes of the capacitor affects its capacitance, the build was pretty easy. There wasn't too much difference between the capacitance of a well made or sloppily-made jar from the same film can. One student made a simple flat capacitor about 4x6" just for fun and it had a capacitance several orders of magnitude larger. Another variation may be to assign a certain dielectric material, plastic or paper or cardboard, etc. and a certain capacitance. Students would have to determine the size of the parallel plate capacitor for that particular thickness of that particular dielectric to achieve that particular capacitance. I feel like it would be more accurate, easier to test and I could judge them based on their accuracy to their hypothetical.
Day 5: Mystery Circuit
This was a variation on my Electric Building (House) Project for regular Physics and Conceptual Physics. I gave each group a shoebox that had a lid with their instructions and made paperclips, brads, wire cutters, wire strippers and holiday lights available. Unlike the previous project students got to design whatever circuit they want as long as it met the conditions:
1. Uses only one 9 V battery.
2. Has at least 8 lights.
3. Has at least 2 switches.
4. All lights can be lit up, all lights have to be able to be turned off (for storage).
Groups were to design their circuits, build it so that just the lights were visible on the outside of the box (rest of wiring hidden on the inside) and make a matching circuit schematic. That earned them the minimum points for accomplishing the task. When they were done each group were to exchange their mystery circuit box with another group and try to guess the schematic. Each group that they successfully stumped earned their a bonus point. I told them that it was quite possible that each group would be stumped and earn points after the exchange.
We did have a few hiccups on this one that I was not anticipating. In my first class of the day we found one LED strand of lights that was masquerading as an incandescent one. Since LEDs are directional it was very difficult for students to build a working circuit with them. And since relative brightness of bulbs is usually how students guess how bulbs are connected the equally bright LEDs wouldn't work for this task. Some of these groups got pretty far into their build before the mistake was recognized and ratified. I had also expected that since students had built a simpler circuit in the same way last year in regular physics they would be able to build this more complicated one quickly. I was wrong. We ended up taking two days to complete this and some groups never did.
There were a few groups that made their circuits so complicated that even they weren't sure how it worked, or the load was too high and it never did. Hurried and/or loose connections made it difficult to judge if their circuits matched their diagrams. Some made simple light connections but used the switches to complicate it, which was more of what I was hoping for, like below:
In the future I think I will limit the number of lights, switches and perhaps more strongly emphasize that all lights must light (not that "Technically a microamp could be flowing through it even though it looks off"). I will have to give them more instructions on how to make the switches, strip wires, etc. I expected students remembered those skills from the previous year; which assumes they did actually build the project they turned in. In the end the activity worked but I wasn't really satisfied with the quality of the project or their efforts.
I had also hoped to keep this year's projects (hence the requirement that they had to be completely turned off) so that perhaps the next year I just asked groups to map the mystery circuits made this year. So few were working a week later when I went to dismantle them that I had to abandon this idea and instead scavenged them for parts. Side note: I take apart all but the very best Electric House projects each year to save the parts (brads, paperclips, bulbs, 9Vs, motors) for the next year.
Day 6:Defibrillator
I got this idea from Frank Nochese on Twitter about challenging students to build a defibrillator model like an RC circuit. I researched defibrillators and put a call into my sister who is a registered nurse to get the low down on how they were actually used and how that related to the circuits my AP students had used. Turns out that the typical movie scene is completely wrong (and a pet peeve of medical professionals everywhere). Usually a patient is shown flat lining (no more heart beat) and it is then that a defibrillator is applied and the doctor charges it up and shouts "Clear!" and a big thwump is heard as the person/ body jumps up on the table. This is repeated until a heart beat is restored. In reality the defibrillator can only be used when there is still a heart beat but it is irregular. A loss of a heart beat means that chest compressions must be applied in order to restart the heart and get it beating again.
When I researched how they actually worked I found that the first prototypes used AC current and modern ones used inductors. I didn't have any inductors so I opted to still use Frank's original plan using an RC (resistor-capacitor) circuit. Real defibrillators use inductors so that the current oscillates, the oscillation can be controlled to match the desired heart beat. An RC circuit model would simulate one "beat" if you will because it would only charge and discharge once. My research led to a few additional questions about defibrillators and the more physics related concepts that I've added to the bottom of the instructions page.
Groups were told that they could use whatever resistors and capacitors they wanted to meet the requirement to save their "patient." I made little paper hospital gowns to go around the "patient" resistor so that students wouldn't get confused when they had multiple resistors in the circuit. It needed a little paper cot as well. These just might turn into fabric ones by next year ...
Each class was assigned a specific "patient" resistance, the maximum current that could go through it and a maximum charge on the capacitor. Groups had to first figure out what their circuit might look like then use those maximum values to determine the specific size capacitor and total resistance to use. I had 100 or 2200 microfarad or 1 farad capacitors for groups to choose from. Almost everyone ended up using the 2200 microfarad. I had a shoebox, literally, of organized resistors for students to work through. They were not as organized when we were done. Some groups couldn't find exactly the value of total resistance they needed but found getting within a few ohms was fine. A few groups wanted to stick to only one resistor (or mistakenly thought that the "patient" resistor was the only one allowed in the circuit) and therefore tried to add a few capacitors in series or parallel.
Once students had built a circuit that allowed them to charge their capacitor (not through their patient) and discharge it through the patient they attached meters. We could probably have done it with multimeters as Frank did initially but I opted for our Vernier voltage and current probes since we had them. Since the currents were in the milliamp range the graphs are so small. Most groups got a good decay curve for the current through the "patient." I had wanted students to also measure the voltage across the capacitor and the resistor but often this was not done due to time.
Next time I won't have all my resistors out. I shudder to think of the order of the envelopes of resistors in that box when I go to look again. I would still have a variety but will try to pair down their options. I did not assign the additional context questions (below) that I wrote this time, they were my backup in case it didn't work at all. Next time I would definitely include them as I like them and think they bring some background to the activity. Other than that I think it was a great lab practical for RC circuits that Frank came up with and I will definitely use it in the future. This is one that I would like to add to my regular curriculum, if we have time.
Day 7: Trivia
This was the Tuesday after Memorial Day weekend, the last real class day before finals. I thought the last day of competition would be a good day to review the material for their final. Rather than using a Jeopardy type format, in which can be slow and often leads to one group keeping control of the game, I opted for a pub trivia format. If you aren't aware a lot of pubs or breweries have Trivia Nights that include teams that come back each week and multi-month tallies of points. Rather than having groups shout out answers or use a buzzer groups submit their answers to questions in writing. Everyone who gets the answer right can get the point, the question move along quickly and you can maintain a bit more decorum. I wrote up over 60 questions spanning the whole Electricity & Magnetism semester, some were multiple choice, some shorter response and some calculations. Each question had a timer for either one minute (conceptual) or two minutes (calculations & short responses) on the slide itself.
Before we began I went over the rules with each class:
•All
groups will be asked the same questions and record their answers on a sheet of
paper to be turned in and graded later.
•NO
CELL PHONES OR OTHER ELECTRONIC DEVICES, TEXTBOOKS OR NOTES ALLOWED. These are
questions to be answered by your brains alone.
•Do
not shout out answers. Do not talk to other groups. Whisper with your group.
•Groups
earn points for each right answer. The group with the most points will earn an
extra 5 points.
•Each
question has a time limit before the next one is shown but you can write
answers to previous questions if you have extra time on another question.
•You
can have more than one paper and pencil out but must turn in one answer sheet.
Groups used whiteboards for their work or discussion/ debate drawings but kept all their "final answers" on a separate piece of paper I would collect at the end. I was able to sit down and read each question as it came up, the counter ticked by and then moved the slide forward for the next one. Students kept on task and most groups attempted all questions. Sometimes there was a lull as they answered a question in less time than was given but sometimes they ran out of time. I encouraged them to record information for questions they ran out of time for so that they could go back on questions that they had extra time for. In the end I collected all the papers and graded them, awarding a point for each right answer. Since there was only one per group it did not take long and sometimes I offered partial credit. The group with the most questions correct also got the bonus points.
What was difficult was the mixing of the questions. We weren't going to get through all 60+ questions in each class so I tried to skip around so that they got a sampling from each major unit (electrostatics, current electricity, magnetism, etc.). This confused some of them as they had to number their answers with the question number which may not have been the number following the last one. There were some questions I wanted every class to get and I found myself having to record on a scratch piece of paper which classes got which question. I'm sure there is a program or website that would improve on this model and I'll have to look for it before next year.
In the end the competition did what I needed it to do: engage the students in some fun physics exploration until the end of the school year. I think my students enjoyed it, especially since they didn't have homework, but it could use some improvements. For one, I don't think it did as good of a job helping them to review for their final exam. Their final exam scores were lower than I would have like, especially since for many it was their only "real" final exam after earlier AP finals. I expected the activities to keep them thinking about the content, which to an extent they did, but it did not help with remembering the finer details and tougher problems they needed to review. Many thought they still knew the material well enough not to have to study, a problem unrelated to the competition.
The points for several groups in each class were quite close, the winners only being a point or half a point ahead of the rest. It was nice to see though that different groups won different competitions. A few groups won twice over the course of the competition (thus earning bonus points) but it was not necessary to be the winner in each class. I would want to tighten up the system of awarding points, try to find activities that require more content knowledge for this semester and increase the difficulty of some of the activities. It wasn't bad for a first run but I anticipate the PhysX-Games of 2019 will be much better.
