Ahhhh... let the fun begin! Lots of really cool activities to help students fully grasp the difficult concept of acceleration. After many years of trying to teach this concept by telling, I'm excited to try out the modeling method to help my students master this topic. The motion of a dynamics car along an incline was studied with a motion sensor and logger pro. Lots of different variations of motion were sampled (cart released from rest, car pushed up the incline, sensor at top, sensor at bottom) with different groups performing different activities and boarding the results. Discussions and questioning followed. We developed an operational definition for acceleration being the "slope of the velocity curve" on a velocity - time graph. We learned a "up up down down" song to help our students understand directional nature of acceleration and velocity and finally showed how the typical kinematic equations (I call them the Fab 4) could be written directly from the graphical data obtained from an experiment in which the car's motion was sampled moving and accelerating down the ramp with the motion sensor starting after the car was in motion (so that we had a non-zero initial velocity and starting position). I found this portion of the unit particularly satisfying as it allows the student an opportunity to see how these equations (a staple of basic kinematics) are "derived" from (or at least accurately model) motion that students created simply by having a car accelerate along a ramp. Seems like it will help take away the mystery, though I'm not sure it will be that meaningful to all students. I think students that either dislike math, or have trouble with it (or both) will not find it all that useful or insightful, but for the "traditional" physics student, I think it will be very useful. We culminated this unit with another practicum whereby we attempted to hit a constant velocity car by rolling a ball down a ramp. A recommendation I have for improving this practicum (something I will do in my class) is to make sure the angle of the ramp is fairly small so that there is a significant time interval for the rolling ball (providing less margin of error). With a steep ramp, the ball will travel the ramp distance in less than 1 second and is fairly easy to hit a moving car. Something even better might be to have the ball travel down the ramp and then along a horizontal section of ground before colliding with the car. This might be too challenging for general classes, but would definitely work with honors or AP classes. 
Again, loved this unit and think there are lots of great ways to help students truly learn acceleration. I plan on implementing every one of these activities and am excited to see how well it works!
Nice entry!
ReplyDeleteI actually think that for the students who feel like they aren't "good at math" who are the same students who don't like it will benefit the most from knowing where the equations come from! It really provides a context for them instead of just having a plug and chug idea. The kids that are good at plug and chug will also have a much better idea about what each of the variable mean.
The real question is how do we then assess students on the model so that it is meaningful. Kinematics problems (like those found in a text book) are not, in my opinion, a good assessment for anything but problem solving and algebra.
We can do better.
During the practicum, each group chose their own parameters like ramp angle. The more you tell the kids what to do the more they rely on you for answers. Because these aren't graded it is OK for the kids to mess up.
Good reflection.