Thursday, April 07, 2016

To CER with Love

We've all asked students to analyze their lab results. Sometimes we have constructed conclusion questions we hope will lead students to the big "aha!" realizations about their data. We may assume more advanced students can recognize connections on their own and just ask them to "write a conclusion." No matter our request, we are often met with students that fall drastically below those expectations, even while others exceed them.

While NGSSifying (sure, it's a word!) your curriculum one relatively easy step is to add Claim-Evidence-Reasoning Conclusions to your existing labs and activities. Often abbreviated as CER (or occasionally as ClEvR) it is a scaffolded method to help students organize the findings of their experiments. It is mentioned specifically in Appendix F Science & Experimentation Practices:

"An explanation includes a claim that relates how a variable or variables relate to another variable or a set of variables. A claim is often made in response to a question and in the process of answering the question, scientists often design investigations to generate data."

You have to start by asking them a question, an open ended one is even better! Perhaps the hardest break from their old habits is to wait until after their experiment to write a claim. It is not a hypothesis to be proved. Their claim is their answer to the question you posed based on their experiment. The next step is to describe their evidence that supports this claim without any explanation. This is difficult for students that are used to runningeverythingtogetherforthesakeoffinishingasfastaspossible. The third and final step is to explain the reasoning behind their evidence.

This is definitely something made more clear with an example. A photocopy of this chart was given to me at a NGSS training years ago and it is still my go-to to explain this method because there is an example for every discipline. When I show this to my students I usually the Earth Science one since they have less experience with that field of science.

Earth Science
How was the Grand Canyon formed?
The Grand Canyon was mainly formed by water cutting into and eroding the soil.
The soil in the Grand Canyon is hard, cannot absorb water and has few plants to hold it in place. When it rains in the Grand Canyon it can rain very hard and cause flash floods. The flash floods come down the side of the Grand Canyon and into the Colorado River.
Water moving can cause erosion. Erosion is the movement of materials on the Earth’s surface. In terms of the Grand Canyon, the water moved the soil and rock from the sides of the Grand Canyon into the Colorado River where it was then washed away.
Some people may think the Grand Canyon was cause by a large earthquake, but the Grand Canyon is not near any tectonic plate boundaries. Furthermore, earthquakes in Colorado are rare and do not tend to be very large - largest earthquake on record had a magnitude of 6.6.

Adapted from “Supporting grade 5-8 Students in Constructing Explanations in Science” (CER) McNeill & Krajcik; Table 2.2 Examples of the Different Components for Scientific Explanations.

I've seen this taught down to the middle school level with graphic organizers representing each step to help guide students into adopting the process. You can find graphics organizers like these (left and right) from a variety of sources, just google "Claim Evidence Reasoning graphic organizers" and you will find lots more. There were even a few that took the shape of a hamburger ...

I've made a poster similar to the example on the right for my room and when a Claim-Evidence-Reasoning format fits our lab experiences I try to use it. So far, it has been about as hit-or-miss as the ol' "Just write a conclusion" format. I think the main reason for that is that I have not embraced it and taught the process repeatedly. Kids know when you half-heartedly attempt something and they reciprocate in kind.

The time I think the format was more successful was during my PVC Dart Gun Lab, a more structured format of the draft I previously posted. I wanted to informally assess the groups and their progress so I printed out quarter sheets with the different questions on them. I wrote the group member's names on them, which also made assigning the groups easier, and asked them to record their Claim-Evidence-Reasoning on it to return to me by the end of the period. It was a quick way to read each and give the groups feedback before they each turned in their own individual labs. I found quite a few that wrote claims as if they were hypothesis, a few more squished their evidence and reasoning together and quite a few more didn't actually offer any evidence despite having collected data. I like to think that this check in helped some students edit their individual labs but having since graded them, I know I didn't get through to them all.

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