The Nail in the Coffin for Cookbook Labs

Around four years ago I came across a lab from a university that led students through finding work and kinetic energy, eventually (hopefully) getting them to the point where they ‘worked’ out the Work-Kinetic Energy Theorem (sorry, I couldn’t resist!). I modified the lab to work with the CBL 2’s I currently had for data collection. Students first found that the area under a force vs displacement graph equaled the work when calculated using  for a constant force. They then moved on to showing that for a non-constant (but linear) spring force, the area under the F vs. d graph was equal to the average force times the displacement, thereby giving credence to the whole area-equals-work idea. Students then allowed a cart to accelerate due to a spring, found the area, found the change in kinetic energy, and saw that they were equal.

The lab had to be fairly scripted, as it required students to collect force and position data, then exit the calculator program, make a graph using lists, fit the data, then find the integral with the correct bounds. I spent a lot of time making sure the instructions were clear.

For the first couple of years I was pretty happy with the results. “Cool, the numbers are the same!” Yep, turns out work equals kinetic energy. This year, however, I re-wrote the instructions for my new Labquests (side note: Of course I get new Labquests right before version 2 comes out!). The instructions weren’t as carefully planned as the previous version, due to lack of time to double check them after writing them, and students struggled. More importantly, each day at the beginning of class I asked what they had learned the day before, and I found that they didn’t seem to have a clue. I almost gave up after the third day went so poorly.

However, the last part of the lab is a comparison between the work done by gravity and the kinetic energy. For this portion of the lab I didn’t hand out the (6 pages for the whole deal!) instructions, instead choosing to give verbal instructions. Students had to work through finding a way to measure the change in height and the final velocity of the cart based on minimal instructions at the start of the class. Anecdotally, I believe students were far more focused on the actual learning, as opposed to spending the bulk of their time trying to decipher the instructions.

As noted in previous posts, I am attempting as much as possible to implement Modeling Instruction, despite lack of training. This experience showed my why the ‘loose’ experimentation of Modeling outperforms strict lab instructions (even when the instructions are a means to inquiry), as students can focus on the data and results rather than if they are ‘doing it right.’ Good timing, given that the funds just came through and I have signed up for my first week of modeling training. I’m very much looking forward to increasing my ability to design modeling scenarios and the resulting increases in student learning.

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