Posted by
Waski_the_Squirrel on Friday, November 23, 2007 1:33:57 PM
I remember Physics in high school. I hated it. One might well ask how someone like me who hated Physics ended up with a degree in Physics. The answer is a great professor in college who helped it all come clear.
In high school, we did no labs in Physics. It was all lecture and problems. The teacher made up problems on the spot. He never learned the lesson I did: problems made up on the spot sometimes can't be solved. It's frustrating (especially to a high school student) to work on homework, fail at it, and then discover all that work was for nothing because the problem was insoluble.
This is not a lament about his teaching style. This is a discussion of labs and technology. At that time (1993-1994) computers weren't in our classrooms yet. We had a computer lab full of Apple IIe's. Admittedly, my school was a bit behind the times. He chose not to do any labs, even with stop watches and simple technology that was available.
I never saw what a high school Physics lab of the day could be until I student taught. (I won't discuss college because much more expensive equipment is available at that level.) When I student taught, in fall of 1998, we used tape timers to take readings of motion.
A tape timer sends a ribbon of paper tape underneath an inked hammer. It leaves dots on the ribbon. By measuring the distance between the dots and knowing the period of the hammer, one can calculate displacement, velocity, and acceleration. The problem with these labs was the incredible amount of time required to do a lab. The kids needed that time to measure each pair of dots and run the calculations. When they had bad readings, they didn't know until they did all the work for, sometimes, 100 pairs of dots. It was ugly!
My first time teaching Physics, I didn't have this equipment. I wound up using stopwatches most of the year. Finally I got frustrated enough to borrow some tape timers from a wealthier school nearby.
Fast forward a bit. I moved to a wealthier school and got an incredible grant to buy 30 graphing calculators. In return for this grant, the school bought CBLs and motion detectors for me. Suddenly, I was in heaven. I could do decent readings of motion. When a student got a bad run, he knew immediately and re-ran the experiment.
The combination of CBL and calculator also gave students a great feel for graphical interpretation. This was actually a step up. My tape-timer students got so lost in tedious calculations that they never got this intuitive feel for motion graphs.
Unfortunately, motion detectors are limited to one dimension, and they don't seem to do so well in reading falling objects.
One year, while teaching projectile motion, it occurred to me to do a lab. I videotaped two students tossing a tennis ball in front of the chalkboard. I then loaded the video into iMovie. Then I advanced it frame by frame and exported each frame as a .jpg file. Then, I loaded the .jpg files into a graphics program called the Gimp. I layered them so that the ball could be seen at each instant as it flew through the air. Finally, I loaded the resulting picture into Geometer's Sketchpad. At that point I realized I had no scale! I was not about to repeat the experiment so I estimated and then plotted points for the ball. After a good 3-4 hours of work, I had a picture and data for my students.

It worked, but what a waste of time. I've reused this picture for a few years now because I have no desire to repeat the time investment. Admittedly, this experiment could not have been done when I was in school.
Technology has moved on. This year I have new software. I can record an experiment with my digital camera, put it on my computer, and just a few minutes later I have something like the above picture. I tried it out this week with a simpler experiment than the above. We dropped a coffee filter and a volleyball. A student stood in the picture with a meter stick so that we could see length. I highlighted the meter stick and then made dots on each frame at the location of the ball and coffee filter. I then had data I could manipulate and use to derive equations.
Now, the ability to study projectile motion from lab data is within the grasp of high school students. The picture below is from the program, but the screen capture I used for this blog didn't show all the dots I made.

My point is that technology is a wonderful thing. Sometimes we make sacrifices. The death of the slide rule destroyed the "intuitive feel" for numbers. This was a sacrifice. However, equipment like that I used in the picture above put the opportunity to work with real data into the hands of high school students. Now, rather than simply work equations, my students can actually see how things work. Furthermore, they can do so with minimal work on my part. After all, the kids should be working, not their teacher!