I haven't heard of that activity and don't want to sound like a commercial, but CAERT (Center for Agricultural and Environmental Research and Training) has some great tools to make the connection to physics standards with lessons. Some states have subscriptions to the curriculum for their teachers. In New Jersey, we have a curriculum called Physical Science Applications in Agriculture which has some lessons. With this resource, you can also search by specific state content standards (i.e. Science and force) to get related lessons. You can find out more at http://www.mycaert.com/state-subscriptions.asp or http://www.caert.org/

I use KNEX and have the students design a mini-tractor using KNEX. After construction we race them using ramps of various height and student calculate speed and other physical science concepts such as if we add more mass what is the implications on the distance traveled and the speed. This is a lesson that I personally made up. If you want more details I would be happy to share them with you. T. Lindberg

I have used the Lego robotic kit with my students to make mini-tractors and then have a tractor pull. The kits are available from Pitsco. I had a grant to purchase one kit then borrowed the other kits. Students worked in groups of 4 and designed and then built their tractor. The only limitations were the number of motors they could put on their tractor. We wound up with 2 divisions: one motor & two motors. I had been advised by another Ag teachers to have the girls together in teams and the boys together in teams. The girls may have started slowly, but their end results were very competitive. The robotic kits allow the students to program changes in direction of the tractor. but this year I only had them go straight and we build a sled to hook behind each tractor and added bolts to the sled as the tractor went down the course. Next year I plan to incorporate a course the tractors will ave to maneuver. I am not sure if I will incorporate backing up or not but I am considering it. I did this activity at the conclusion of a Ag Robotics unit. The students enjoyed it and participated extremely well. I told the school system Science Coordinator about it and she showed up to take pictures which she posted on the home page of the website and then it was included in the system budget proposal for next year's budget.