Sunday, January 29, 2017
Analyzing a simple Crash Cushion design
When my students make their crash cushions many of them create paper tubes. This can lead to a successful design or a horrible one. I saved one such simple design and tested it in three different orientations. Depending on the level of your students you could show them this to aid with their own design development.
Tuesday, January 24, 2017
Crash cushions cont.
Several years ago Dan Burns and I started discussing an engineering project for which students build a crash cushion to investigate momentum and impulse. Using only a few sheets of paper and hot glue student groups design crash cushions (similar to water barrels or guard rails on roadways) to lower the force experienced by a cart rolling down an incline that crashes into them.
Since then we have both completed the project with classes albeit differently. We also presented at the Summer 2016 AAPT meeting in Sacramento, all of the materials discussed there are here. I wanted to share the project here again, with the tweaks my partner Jon Brix and I have made to it since.
My colleague Matt Miller continued the project in Conceptual Physics this year although opted not to use the Vernier sensor that I had last year. He opted for the resettable Drop N Tells I bought years ago instead as it is more visual for the younger students. He set up a ramp and used a lightweight impact car that had an additional <200 grams of mass added. Miller adjusted the ramp set-up until the 25, 15, 10 and 5-g sensors were consistently tripping. His students were challenged to design the crash barrier that did not trigger all the sensors. I believe he set the grading up this way:
C = triggering the 15, 10 and 5-g sensors
B = triggering the 10 and 5-g sensors
A = triggering only the 5-g sensor
Extra Credit earned for not triggering any sensors.
Dan uses a PASCO Smart Cart while I use Vernier sensors. The first year I tried this I used a low-g accelerometer because it was what I had. Through a Donors Choose grant I was able to purchase the higher 25-g accelerometer, 3-axis accelerometer and a Wireless Dynamic Sensor System (WDSS). The wired sensors require some coordination to prevent the cord from catching but are workable. I found that the wireless WDSS made for easier set-ups but would disconnect occasionally. Both the WDSS and the 3-axis sensors were almost too accurate and the graphs produced were difficult for students to interpret. I opted this year to use the single-axis 25-g accelerometer because even collecting 500 samples per second the peak accelerations were easier for students to determine.
In the past I've used a wood ramp and a big heavy dynamics cart that then travels along the flat lab bench into a wall. The transition from ramp to flat tabletop caused additional acceleration peaks so we opted to have the cart run directly into the wall from an incline. The heavy cart and steep ramp produced a high acceleration that exceeded the accelerometer's limits. We decreased the ramp angle and still occasionally "missed" the hit because the time of impact of the cart against the wall was so short. This year we opted to use a low-friction (not smart) PASCO cart and track from another colleague. The 120 cm long track was raised above the table by one textbook and pushed against the wall. A box of weights (over 30 lbs) was pushed against the higher end of the track to prevent it from moving. In initial tests the conservation of momentum caused the track to move quite a bit when the cart struck the end of the track.
This year student designs proved very successful. Because of the light cart and small incline students were able to reduce the acceleration of the cart at impact fairly easily. Usually the designs that "failed" did so because the cart passed underneath the crash cushion and still struck the wall. I had only one set-up in the classroom so groups took turns testing their barriers and collecting data. We stored a trial of the cart running into a book at the end of the ramp and then printed out graphs for each group with their trial on top of the control data. Here is an example of the data student's received with the control (green) and their trial (blue):
Students were to take measurements of their crash cushion before and after their collision although most cushions did not permanently deform. For some reason students were very pleased when their crash cushion suffers little damage; several cited the fact that it could be reused as a positive attribute. Students were also to calculate the Force with and without their crash cushion based on the mass of the cart.
Using this information students were to write a Claim, Evidence, Reasoning (CER) conclusion to answer the question: "Was your crash cushion effective?" After grading these conclusions we realized a few things:
1. Students did not agree on what made a crash cushion effective. Most students realized that decreasing the force, as shown on their graph as a decrease in acceleration, by increasing the time of impact made for a successful crash cushions. A few more realized that stopping the moving cart without letting it bounce back was also good. Yet many students considered their crash cushions ineffective if there was any acceleration, even if they reduced their force by more than 50% .
2. Students do not know what is fact vs. opinion. This must be going around recently. Students often stated opinions or qualitative observations in place of specific measurable data. "Our crash cushion was good because it stopped the cart slowly."
3. Some students did not understand the graph axis, significance of peaks, etc. Referring to the example above, some students incorrectly described the "time of impact" to be just over 2.5 seconds for the control trial. They did not understand or forgot the fact that the cart had to roll down the ramp before the impact.
4. When in doubt, students are prolific. I expected three, maybe 5, sentences from students yet often received a full page. While grading these conclusions I often crossed out over half of what was written because it was superfluous. They seemed to just keep writing and praying for partial credit.
Before handing back their conclusions I reviewed the CER format with students and showed them a few pictures of correctly written (short) examples of their peers. I showed them a few sample graphs from their trials and reviewed the significance of each peak. In the future this will be done the day after to give students a chance to correct their CER conclusions before turning them in.
Since then we have both completed the project with classes albeit differently. We also presented at the Summer 2016 AAPT meeting in Sacramento, all of the materials discussed there are here. I wanted to share the project here again, with the tweaks my partner Jon Brix and I have made to it since.
My colleague Matt Miller continued the project in Conceptual Physics this year although opted not to use the Vernier sensor that I had last year. He opted for the resettable Drop N Tells I bought years ago instead as it is more visual for the younger students. He set up a ramp and used a lightweight impact car that had an additional <200 grams of mass added. Miller adjusted the ramp set-up until the 25, 15, 10 and 5-g sensors were consistently tripping. His students were challenged to design the crash barrier that did not trigger all the sensors. I believe he set the grading up this way:
C = triggering the 15, 10 and 5-g sensors
B = triggering the 10 and 5-g sensors
A = triggering only the 5-g sensor
Extra Credit earned for not triggering any sensors.
Dan uses a PASCO Smart Cart while I use Vernier sensors. The first year I tried this I used a low-g accelerometer because it was what I had. Through a Donors Choose grant I was able to purchase the higher 25-g accelerometer, 3-axis accelerometer and a Wireless Dynamic Sensor System (WDSS). The wired sensors require some coordination to prevent the cord from catching but are workable. I found that the wireless WDSS made for easier set-ups but would disconnect occasionally. Both the WDSS and the 3-axis sensors were almost too accurate and the graphs produced were difficult for students to interpret. I opted this year to use the single-axis 25-g accelerometer because even collecting 500 samples per second the peak accelerations were easier for students to determine.
In the past I've used a wood ramp and a big heavy dynamics cart that then travels along the flat lab bench into a wall. The transition from ramp to flat tabletop caused additional acceleration peaks so we opted to have the cart run directly into the wall from an incline. The heavy cart and steep ramp produced a high acceleration that exceeded the accelerometer's limits. We decreased the ramp angle and still occasionally "missed" the hit because the time of impact of the cart against the wall was so short. This year we opted to use a low-friction (not smart) PASCO cart and track from another colleague. The 120 cm long track was raised above the table by one textbook and pushed against the wall. A box of weights (over 30 lbs) was pushed against the higher end of the track to prevent it from moving. In initial tests the conservation of momentum caused the track to move quite a bit when the cart struck the end of the track.
This year student designs proved very successful. Because of the light cart and small incline students were able to reduce the acceleration of the cart at impact fairly easily. Usually the designs that "failed" did so because the cart passed underneath the crash cushion and still struck the wall. I had only one set-up in the classroom so groups took turns testing their barriers and collecting data. We stored a trial of the cart running into a book at the end of the ramp and then printed out graphs for each group with their trial on top of the control data. Here is an example of the data student's received with the control (green) and their trial (blue):
Using this information students were to write a Claim, Evidence, Reasoning (CER) conclusion to answer the question: "Was your crash cushion effective?" After grading these conclusions we realized a few things:
1. Students did not agree on what made a crash cushion effective. Most students realized that decreasing the force, as shown on their graph as a decrease in acceleration, by increasing the time of impact made for a successful crash cushions. A few more realized that stopping the moving cart without letting it bounce back was also good. Yet many students considered their crash cushions ineffective if there was any acceleration, even if they reduced their force by more than 50% .
2. Students do not know what is fact vs. opinion. This must be going around recently. Students often stated opinions or qualitative observations in place of specific measurable data. "Our crash cushion was good because it stopped the cart slowly."
3. Some students did not understand the graph axis, significance of peaks, etc. Referring to the example above, some students incorrectly described the "time of impact" to be just over 2.5 seconds for the control trial. They did not understand or forgot the fact that the cart had to roll down the ramp before the impact.
4. When in doubt, students are prolific. I expected three, maybe 5, sentences from students yet often received a full page. While grading these conclusions I often crossed out over half of what was written because it was superfluous. They seemed to just keep writing and praying for partial credit.
Before handing back their conclusions I reviewed the CER format with students and showed them a few pictures of correctly written (short) examples of their peers. I showed them a few sample graphs from their trials and reviewed the significance of each peak. In the future this will be done the day after to give students a chance to correct their CER conclusions before turning them in.
Saturday, January 07, 2017
Where the Bolts Are
Exploratorium genius, Paul Doherty, recently shared this gem of a resource. It's a real-time visual representation of lightning all around the world.
LightningMaps.org
LightningMaps.org
Christmas Convection: The Fiery Fairy
I might very well be the last high school physics teacher teaching the topics of temperature, thermal expansion, heat, and heat transfer. Don't worry, I'll eventually retire and that will be that. (As it is, I've relegated those delicious topics to AP Physics 2, and that course is subject to the whims of enrollment.)
In the meantime, here's a tidbit that I'll be adding this sparking gem of black humor to my convection curriculum.
In my assessment, the flying fairy is a sensitive sensor for air currents in a room. And the fireplace sets up a "negative pressure" by sending heated air up the chimney and drawing air in from the living room. The fairy successfully discovered this air current. Great Success!
The video above went viral a few years ago. And some clever folks produced a satirical follow-up: Fiery Fairy Funeral.
In the meantime, here's a tidbit that I'll be adding this sparking gem of black humor to my convection curriculum.
In my assessment, the flying fairy is a sensitive sensor for air currents in a room. And the fireplace sets up a "negative pressure" by sending heated air up the chimney and drawing air in from the living room. The fairy successfully discovered this air current. Great Success!
The video above went viral a few years ago. And some clever folks produced a satirical follow-up: Fiery Fairy Funeral.
Monday, January 02, 2017
Normalize Science
Most people that know me realize I'm a "science nerd," probably more appropriately described as a "science enthusiast." This means I enjoy talking about, reading about and encouraging others to learn about science. Most science teachers I know are enthusiastic enough about their subjects that they randomly insert science into everyday conversations. Sometimes this is greeted with "Hey that's interesting! Thanks for sharing!" type comments. Other times our science related comments are met with awkward science and a change of subject. This happened several times over the holidays and I was struck by how unusual it seemed to be to "talk science."
At both the extended family Christmas Eve and our neighborhood New Years Eve party I shared our plans for a family trip to see the Great American Eclipse next August. It is common when this comes up to have to explain to an otherwise well educated adult what a solar eclipse is and how it happens. At each holiday party I asked kids not "How's school going?" but "What are you learning in science class this year?" When the horn a child was blowing at a party seemed too loud I broke out the decibel meter app on my phone and reminded a mechanic friend to wear hearing protection at work.
My active and conscious support of science for all also presents with gift exchanges. I try to buy science or educational gifts for our family and friends, which I sometimes have to explain after they open it. For instance, this year I gave an Airzooka, a favorite classroom demonstration, to a family member who had received mostly gift cards from the rest of the family. As a young teenage boy he is now "difficult to buy for" and "doesn't want toys." As this video explains the Airzooka pushes a pocket of air that can be felt across the room. As soon as I assembled it for him he began shooting air at others across the room, and soon adults of all ages were stealing it to play with it. They had never seen anything like it, all wanted to know where to buy it and wanted to hear how it worked. Of course I was happy to oblige them and explain the science of it and how I use it to model sound waves in class. Family and friends were surprised how fun the Airzooka and other gifts were since they knew they were science and education related. Somehow labeling them that way came with the assumption that they couldn't be fun or couldn't be for younger kids. We've also given a drinking bird, geodes to crack, a moon night light with lunar phases, a solar robot toy, and more.
Luckily, other friends and families asked what my kids' interests are or if I have any specific ideas for them. They received many science and educational toys this year and I'm happy to report they are loving them all so far. Their Nana gave them Code-A-Pillars which allows them to build a robot caterpillar by connecting segments with different instructions on each. It allows students to practice rudimentary programming and learn sequencing. GG (Great Grandma) got my six-year-old a special viewing planter that allows her to see the plant roots as they develop. And a good family friend obliged when I said she really wanted a toy metal detector and she happily pranced around the yard listening to it ping.
While many science teachers already talk with their friends and family about science or give the gift of science, I'd love to see such practiced by non-scientists as well. A common phrase these days is "We need to normalize [X, Y or Z]." One way to normalize science for all is to talk about it. When someone around you asks "Why did that happen?" or "I wonder if..." discuss it with them, even if you don't know the answer. Encourage the young ones around you to be interested in science, even if they "don't want to be scientists." People like to cook, even if they aren't chefs. They like to go for bike rides even if they don't have professional equipment. I would argue that science can be an interest or a hobby for everyone. All adults can dabble in science without having a degree in science and they can encourage every child around them to do the same. Coloring became a viral sensation and the hobby-du-jour; let's make science the thing to do this year.
At both the extended family Christmas Eve and our neighborhood New Years Eve party I shared our plans for a family trip to see the Great American Eclipse next August. It is common when this comes up to have to explain to an otherwise well educated adult what a solar eclipse is and how it happens. At each holiday party I asked kids not "How's school going?" but "What are you learning in science class this year?" When the horn a child was blowing at a party seemed too loud I broke out the decibel meter app on my phone and reminded a mechanic friend to wear hearing protection at work.
My active and conscious support of science for all also presents with gift exchanges. I try to buy science or educational gifts for our family and friends, which I sometimes have to explain after they open it. For instance, this year I gave an Airzooka, a favorite classroom demonstration, to a family member who had received mostly gift cards from the rest of the family. As a young teenage boy he is now "difficult to buy for" and "doesn't want toys." As this video explains the Airzooka pushes a pocket of air that can be felt across the room. As soon as I assembled it for him he began shooting air at others across the room, and soon adults of all ages were stealing it to play with it. They had never seen anything like it, all wanted to know where to buy it and wanted to hear how it worked. Of course I was happy to oblige them and explain the science of it and how I use it to model sound waves in class. Family and friends were surprised how fun the Airzooka and other gifts were since they knew they were science and education related. Somehow labeling them that way came with the assumption that they couldn't be fun or couldn't be for younger kids. We've also given a drinking bird, geodes to crack, a moon night light with lunar phases, a solar robot toy, and more.
Luckily, other friends and families asked what my kids' interests are or if I have any specific ideas for them. They received many science and educational toys this year and I'm happy to report they are loving them all so far. Their Nana gave them Code-A-Pillars which allows them to build a robot caterpillar by connecting segments with different instructions on each. It allows students to practice rudimentary programming and learn sequencing. GG (Great Grandma) got my six-year-old a special viewing planter that allows her to see the plant roots as they develop. And a good family friend obliged when I said she really wanted a toy metal detector and she happily pranced around the yard listening to it ping.
While many science teachers already talk with their friends and family about science or give the gift of science, I'd love to see such practiced by non-scientists as well. A common phrase these days is "We need to normalize [X, Y or Z]." One way to normalize science for all is to talk about it. When someone around you asks "Why did that happen?" or "I wonder if..." discuss it with them, even if you don't know the answer. Encourage the young ones around you to be interested in science, even if they "don't want to be scientists." People like to cook, even if they aren't chefs. They like to go for bike rides even if they don't have professional equipment. I would argue that science can be an interest or a hobby for everyone. All adults can dabble in science without having a degree in science and they can encourage every child around them to do the same. Coloring became a viral sensation and the hobby-du-jour; let's make science the thing to do this year.
Sunday, December 11, 2016
Make your own Transit Light Curves
I highly recommend the educational activities from SETI; especially their Kepler Mission materials found here. There are NGSS aligned activities arranged by age level. I'm looking into the Transit Tracks activities to link Kepler's equations with the Kepler mission, light and our Universal Gravitation unit.Within that document SETI describes a demo of the Kepler mission by passing a bead on a string in front of a light bulb in a dark room. There is a note off to the side that says:
Optional: Collect Real Data
If you have a light sensor, computer with sensor interface, graphing software, and a computer display projector, place the light sensor in the plane of the planet/ bead orbit and aim sensor directly at the light. Collect brightness data and project the computer plot in real time. Let the students comment on what they are observing. Instead of swinging beads, you may use a mechanism, known as an orrery, to model the planets orbiting their star. Instructions for building an orrery from LEGO™ parts may be found on the NASA Kepler Mission website at http://kepler.nasa.gov/education/ModelsandSimulations/LegoOrrery/
I don't have Vernier light sensors but I do have the Physics Toolbox Suite on my phone which uses the light sensor already on your phone. The app is free and has many different tools all using the internal properties of your phone. I find myself using it frequently and if I ever get tablets for my classroom I'll be using this much more frequently.
I played around with the idea over the weekend using a dim kid's light and passes my hand in front of it to model a transit. At first I tried a ceiling mounted light but I found that since its a CFL bulb there were small variations in the light that might confuse students. In class I would be using incandescent light bulbs anyway. The kids' dim flashlight had a fairly consistent output and the dips were caused by my hand in front of it in a completely dark room.I would like to model something smaller than the light source like the bead on a string that SETI suggested. It will also be a good lesson about the difficulties of the mission as students won't see too much of a reduction in light unless the shadow of the bead passes right over the sensor on the phone. I don't have orreries but can challenge students to keep constant period orbits. Perhaps by next year I can develop something super simple like this DIY Orrey.
The nice folks in charge of the @PhysicsToolbox twitter account pointed out this The Physics Teacher article on the subject sing their light sensor for something similar.
After students learn how to read Transit Light Curves from the SETI activity I hope to have them make their own and model the same graph interpreting skills. It will only take one kid with a phone in each group to make this work and I think I'll have that covered.
Saturday, December 03, 2016
Roll the dice
Studying the Law of Universal Gravitation can be heavy (ba dum tss) for students. Each year my students push through the long equations and we go without a lab for about a week. That's pretty unusual in my classes and they can feel the change. If a student asks why we aren't doing a lab I usually reply, "Well I can't haul Jupiter in here to measure it so ...."
Practice problems were always difficult for students, more about living by the Order of Operations (PEMDAS) then actually understanding the problem. Some would take one look at that period of revolution equation and say "No, nuh uh, not gonna make me. Nope."
I tried to make them fun by creating word problems. It wasn't just calculating the Force of Gravity between you and Jupiter, "Let's compare that to the Force of Gravity between you and the doctor that delivered you! Jupiter's gravity doesn't affect you and astrology is bunk!" But still going through problems together wasn't engaging students.
A few years ago I had an idea to make our practice calculations into a dice game. One di has problems to solve and the other different planets. There are actually two different planet di so that students can choose. Here is a print ready file, I suggest thicker paper to give it some structure. They take some time to assemble but you can use them for years to come.
The kids loved it. They probably work through more practice problems than they would have if I had just supplied them with certain ones to do and they were very invested in letting chance choose which they would calculate. A new development this year was that they are so used to checking their answers with me while they whiteboard they wanted to know the "answer." That was harder to do as I walked around the room since there were so many variations. I decided to create and project an answer chart in Excel.
Depending on how your school or district is defining "physics" from the NGSS framework you may or may not be finding yourself teaching more Earth & Space Science. We had our own sort of NGSS Draft among Chemistry, Physics and Biology trying to divide up the Earth & Space Science topics. In my district Physics ended up, rightly so I feel, with HS-ESS1-4:
This goes well with HS-PS2-4 about the Law of Universal Gravitation:
I'm still working on adding more of Kepler's Laws into the curriculum, there is an outline here on this Disciplinary Core Idea about it.
Practice problems were always difficult for students, more about living by the Order of Operations (PEMDAS) then actually understanding the problem. Some would take one look at that period of revolution equation and say "No, nuh uh, not gonna make me. Nope."
I tried to make them fun by creating word problems. It wasn't just calculating the Force of Gravity between you and Jupiter, "Let's compare that to the Force of Gravity between you and the doctor that delivered you! Jupiter's gravity doesn't affect you and astrology is bunk!" But still going through problems together wasn't engaging students.
| Your birth Mass (kg) | Jupiter & Doctor (kg) | closest distance (m) | Universal Gravitational Constant | Force of Gravity (N) |
| 4 | 1.90E+27 | 588000000000 | 6.67E-11 | 1.47E-06 |
| 4 | 100 | 0.1 | 6.67E-11 | 2.67E-06 |
The kids loved it. They probably work through more practice problems than they would have if I had just supplied them with certain ones to do and they were very invested in letting chance choose which they would calculate. A new development this year was that they are so used to checking their answers with me while they whiteboard they wanted to know the "answer." That was harder to do as I walked around the room since there were so many variations. I decided to create and project an answer chart in Excel.
Depending on how your school or district is defining "physics" from the NGSS framework you may or may not be finding yourself teaching more Earth & Space Science. We had our own sort of NGSS Draft among Chemistry, Physics and Biology trying to divide up the Earth & Space Science topics. In my district Physics ended up, rightly so I feel, with HS-ESS1-4:
| HS-ESS1-4. | Use mathematical or computational representations to predict the motion of orbiting objects in the solar system.[Clarification Statement: Emphasis is on Newtonian gravitational laws governing orbital motions, which apply to human-made satellites as well as planets and moons.] [Assessment Boundary: Mathematical representations for the gravitational attraction of bodies and Kepler’s Laws of orbital motions should not deal with more than two bodies, nor involve calculus.] |
|---|
| HS-PS2-4. | Use mathematical representations of Newton’s Law of Gravitation and Coulomb’s Law to describe and predict the gravitational and electrostatic forces between objects. [Clarification Statement: Emphasis is on both quantitative and conceptual descriptions of gravitational and electric fields.] [Assessment Boundary: Assessment is limited to systems with two objects.] |
|---|
Wednesday, November 23, 2016
Understanding Even More Car Crashes
I posted a lesson to accompany the IIHS "classic", Understanding Car Crashes a few years ago. If that post doesn't ring a bell, click here. Links to the video and lesson can be found in that original post.
A related story percolated up through my social media feed a few days ago. National Public Radio's Goats and Soda produced a story about the Latin New Car Assessment Program (NCAP). NCAP ran a crash test that pitted entry level Nissan vehicles against each other: The American Versa vs. the Mexican Tsura.
Crash Test Dummies Show The Difference Between Cars In Mexico And U.S.
Here's the video:
2015 Nissan Tsura vs. 2016 Nissan Versa
[Executive summary: The American passenger fares much better than Mexican passenger.]
When news of the test went public, Nissan announced that Nissan Mexico would discontinue sales of the Tsura in a few months.
It could be that the timing of Nissan's announcement coinciding with NCAP's test was... coincidental. That is a real possibility.
On a tangentially related oldie-but-goodie, some folks think cars from yesteryear were tanks that would decimate today's light-weight counterparts. An instuctive crash test pits a 2009 Impala against a 1959 Bel Air. Watch the video to see how that one turned out.
2009 Chevrolet Impala vs. 1959 Chevrolet Bel Air
If you're a classic car enthusiast, drive carefully!
The lesson I constructed includes an exercise in which students look up the IIHS safety test of the car they drive (or are commonly driven in).
A related story percolated up through my social media feed a few days ago. National Public Radio's Goats and Soda produced a story about the Latin New Car Assessment Program (NCAP). NCAP ran a crash test that pitted entry level Nissan vehicles against each other: The American Versa vs. the Mexican Tsura.
Crash Test Dummies Show The Difference Between Cars In Mexico And U.S.
Here's the video:
2015 Nissan Tsura vs. 2016 Nissan Versa
[Executive summary: The American passenger fares much better than Mexican passenger.]
When news of the test went public, Nissan announced that Nissan Mexico would discontinue sales of the Tsura in a few months.
It could be that the timing of Nissan's announcement coinciding with NCAP's test was... coincidental. That is a real possibility.
On a tangentially related oldie-but-goodie, some folks think cars from yesteryear were tanks that would decimate today's light-weight counterparts. An instuctive crash test pits a 2009 Impala against a 1959 Bel Air. Watch the video to see how that one turned out.
2009 Chevrolet Impala vs. 1959 Chevrolet Bel Air
If you're a classic car enthusiast, drive carefully!
The lesson I constructed includes an exercise in which students look up the IIHS safety test of the car they drive (or are commonly driven in).
Saturday, November 19, 2016
Inertia of Fall Leaves
This video has gone viral with good reason, its super cool.
In this slow mo video we see an amazing example of inertia as the bed of leaves remain as the net is lowered beneath them. What else can you discuss about with this video?
In this slow mo video we see an amazing example of inertia as the bed of leaves remain as the net is lowered beneath them. What else can you discuss about with this video?
Evolution of Physics Curriculum
As I NGSSify my curriculum I find myself removing some pieces of my curriculum that I've done for a long time. Sometimes they are replaced with better activities, sometimes they were dead weight, sometimes I'm sad to see them go. I'm not there yet but it is a process for which we still have several years as the NGSS assessments might be ready by 2018. You've got some time.
While making these curriculum choices I ask myself:
- Does this activity align with NGSS in content (addressing a Discipline Core Idea or Performance Expectation)?
- Or does it align with the Science & Engineering Skills?
- If not is it an essential skill to support NGSS acquisition? (i.e. graph making)
- Is it content that they need to support late NGSS content? (i.e. Newton's 1st and 3rd Laws)
As we approach the middle of the 2nd quarter I find that I am "behind" my past self by almost two weeks. This has meant moving Energy, Work & Power to second semester rather than cram it in first semester. My time crunch is due to a few big changes in my classroom that are still getting the kinks worked out:
1) This year I do not have required homework other than finishing labs. There are some "suggested homework" each night and the problems that I really like are worked into the class period. I suggest that struggling students do the homework each night, it is very briefly reviewed each day because less than a quarter of the students do it nightly. A lot of my students are in more than one AP class, sometimes I am their only non AP class, so if they are understanding the material they don't have to "waste" time doing homework if they don't need it.
2) So how do students know they should try the optional homework? Each week students take a low-stake weekly quiz based on the homework. That way they and I know how they well they are understanding the concepts. I grade their notebooks at the same time so that I can look over their labs for the week. Timing has been an issue so far. Sometimes the quizzes are too long and take most of the period. Absences have also delayed getting the quizzes passed back so in the future I think I will excuse the absent kids. This mean I don't have a chance to see how they are doing before the big assessment and the other quizzes in that category count more but it should improve the pass back time. I want students to have near immediate feedback on these formative assessments. I have been crudely tracking the standards addressed in each quiz in an Excel sheet but they have not been in a way that can be easily shared.
3) Students complete problems on whiteboards in small groups. This has been successful but sometimes not universally so depending on a few things. Some students dominate whiteboards just as they do labs so now I ask students to pass the marker on after each problem. Some students don't feel confident enough in their abilities to problem solve while others are watching. If the group is motivated to be "done" as fast as possible then they miss out on the conversations and growth to get something written ASAP. Yet some of the best problem solving think-out-loud collaborating discussions my students have ever had have taken place this year. They correct each other by citing previous activities, "Remember when she said this? Remember that one lab we did?".
Overall I like the changes and will be keeping them, with some revisions. I need to focus on making sure the weekly quizzes tackle common misconceptions just as much as calculation practice. I need to emphasize and normalize doing the suggested homework without making it seem required. It should feel like an opportunity for students; I want struggling students to want to do it to improve themselves. For whiteboards we have to set up community expectations that include all the students of the group at once and makes it a safe space for all of them to try, make mistakes and try again. And I have to work on my timing by probably further cutting some material. But that will be a topic for another post ...
While making these curriculum choices I ask myself:
- Does this activity align with NGSS in content (addressing a Discipline Core Idea or Performance Expectation)?
- Or does it align with the Science & Engineering Skills?
- If not is it an essential skill to support NGSS acquisition? (i.e. graph making)
- Is it content that they need to support late NGSS content? (i.e. Newton's 1st and 3rd Laws)
As we approach the middle of the 2nd quarter I find that I am "behind" my past self by almost two weeks. This has meant moving Energy, Work & Power to second semester rather than cram it in first semester. My time crunch is due to a few big changes in my classroom that are still getting the kinks worked out:
1) This year I do not have required homework other than finishing labs. There are some "suggested homework" each night and the problems that I really like are worked into the class period. I suggest that struggling students do the homework each night, it is very briefly reviewed each day because less than a quarter of the students do it nightly. A lot of my students are in more than one AP class, sometimes I am their only non AP class, so if they are understanding the material they don't have to "waste" time doing homework if they don't need it.
2) So how do students know they should try the optional homework? Each week students take a low-stake weekly quiz based on the homework. That way they and I know how they well they are understanding the concepts. I grade their notebooks at the same time so that I can look over their labs for the week. Timing has been an issue so far. Sometimes the quizzes are too long and take most of the period. Absences have also delayed getting the quizzes passed back so in the future I think I will excuse the absent kids. This mean I don't have a chance to see how they are doing before the big assessment and the other quizzes in that category count more but it should improve the pass back time. I want students to have near immediate feedback on these formative assessments. I have been crudely tracking the standards addressed in each quiz in an Excel sheet but they have not been in a way that can be easily shared.
3) Students complete problems on whiteboards in small groups. This has been successful but sometimes not universally so depending on a few things. Some students dominate whiteboards just as they do labs so now I ask students to pass the marker on after each problem. Some students don't feel confident enough in their abilities to problem solve while others are watching. If the group is motivated to be "done" as fast as possible then they miss out on the conversations and growth to get something written ASAP. Yet some of the best problem solving think-out-loud collaborating discussions my students have ever had have taken place this year. They correct each other by citing previous activities, "Remember when she said this? Remember that one lab we did?".
Overall I like the changes and will be keeping them, with some revisions. I need to focus on making sure the weekly quizzes tackle common misconceptions just as much as calculation practice. I need to emphasize and normalize doing the suggested homework without making it seem required. It should feel like an opportunity for students; I want struggling students to want to do it to improve themselves. For whiteboards we have to set up community expectations that include all the students of the group at once and makes it a safe space for all of them to try, make mistakes and try again. And I have to work on my timing by probably further cutting some material. But that will be a topic for another post ...
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