Exploring Energy Conservation with rulers and cars

This activity is designed for students to employ and carry out the steps of the scientific method.
This activity is designed for students to demonstrate transfer of information through writing.
This activity is designed for students to demonstrate understanding of the law of conservation of energy.
Students will employ synthesis and writing skills.
Concepts: Energy cannot be created or destroyed, it merely changes forms. Potential energy is stored energy. Kinetic energy is the energy of motion.
Vocabulary: Velocity, Elastic, Variable

This lab activity is intended for a 9th grade physical science class towards the end of a unit on energy. The activity could take anywhere from 30 minutes to 90 minutes, depending on how complete and finished the students' lab reports are to be. Besides dealing with energy, students should be familiar with good lab procedure design including RERUN conclusion writing. The activity could easily be modified for a higher level physics class simply by including more calculations or using the lab as an introduction to the unit.

Materials: (for each team) flexible ruler (meter stick ok), hot wheels/matchbox car, stopwatch, masking tape

Lesson:
Have the students form into lab teams. Assign roles to the team members: Team Leader, Materials Manager, Notes Manager, Time Keeper.

Describe the investigation to the students:
"This is a three part activity. Part one will be preliminary design, Part two will be procedure development and Part three will be the investigation."
Part One: "Using a ruler and car, your team needs to design a lab that can exploit the Law of Conservation of Energy to change one form of energy into another. Once I say "go," you will have 7 minutes to outline the procedure for such a lab. You will not be able to use the materials yet, so you must sketch out a design to show me. Once that is complete we will move onto part 2." Teacher should open the floor to questions and once all questions are answered, begin the 7 minutes.
Part Two: "Now, using your lab design as a tool, come up with a hypothesis for how you could maximize the amount of energy transfer. Once you have a hypothesis, create a procedure for proving your hypothesis." Teacher should check all teams' work to make sure they are on the right track. Make sure they make reference to variables.
Part Three: "Carry out your procedures. Make your measurements are as accurate as you can. Remember to use RERUN format for your conclusions."
Once the labs are complete, students could turn in their data and conclusions. Alternatively, students could have extra time to type their reports and include graphs. Once all labs are turned in, the teacher could have different teams discuss the methods they created and also the results. Lab report format (Microsoft Word 25kB Aug28 07) RERUN conclusion - source unknown (Microsoft Word 25kB Aug28 07)

Students may need help with the report format, depending on how much you've done it before. There are at least three ways to design the lab. One is to use the ruler as a ramp and let the car roll down. Another is to use the ruler as a horizontal "catapult" by bending it and having it slap the car. A third is to use the ruler as a vertical catapult. This one actually converts elastic potential energy into gravitational potential energy and then kinetic energy, so students might need guidance in what to measure. I've never done this lab before, so I'm not sure what might go wrong.

Students will turn in their individual lab reports. I will read their lab reports, paying special attention to their conclusions and data. The reports will be assessed with a standard rubric.

9-12 Physical Science: II.C.1, II.C.5, I.B.1