## Overview

Students continue working on their wind-ups, recording the issues that come up.  They are introduced to the concepts of "potential energy", "elastic energy", and "kinetic energy."

## Materials

• Partially completed wind-ups from Lesson 1.
• Same materials for making wind-ups as in lesson 1 plus materials for new wind-ups for those who finish early: large and small wheels, different cups and tubes to place between the wheels.

## Procedure

1. Wind-up issues and energy: In a class meeting discuss the issues students have encountered. Chart the issues that students raise. Introduce the concepts of potential energy, elastic energy, and kinetic energy. Demonstrate these concepts with the wind-up:

• When I wind the stick, I move. This moving is kinetic energy. Where does my energy go?
• My kinetic energy goes into twisting the rubber band, where it is stored as elastic energy. Elastic energy is potential energy. It is ready to make something move.
• What happens to the potential energy stored in the rubber band, when I let the wind-up go?
• The potential energy in the rubber band is used to make the wind-up go. Potential energy is changed into the energy of motion which is called  kinetic energy.

If available, show a video or read a book on the different forms of energy

2. Making wind-ups: Students continue working on their wind-ups. Students who have already made wind-ups can  make new ones of different types. Provide them with samples of wind-ups with large wheels, small wheels, wheels of different size.  As students are working, ask them to keep track of issues that arise. Post the issues on chart paper. Keep this chart for use in Lessons 3 and 5. As students ask for help with problems, identify these as issues, by adding them to the chart. Some examples of issues that are likely to come up:

• The rubber band won’t go through the holes.
• The wind-up won’t stay together.
• The wind-up does nothing at all.
• The wind-up moves but won’t go in a straight line.
• The wind-up moves, but spins in place instead of traveling
• I would like the wind-up to go farther
• I would like the wind-up to go faster
Here is one explanation why some wind-ups go far and others go fast (or spin out).

3. Science Notebook:

• Compile an Issues List, including anything that didn’t work the way you wanted it to.
• Complete the worksheet "The Wind-up I made.".

4. Outcomes

• Students learn to isolate problems. You can’t usually solve a problem until you know what it is.
• Word wall words:  potential energy, stored energy, elastic energy, kinetic energy, energy of motion, issues.

## Troubleshooting

Students encounter many issues as they try to construct the wind-up and make it go the way they want it to go.  Here are videos that address many of the issues.
1. The rubber band won’t go through the holes.
2. The wind-up won’t stay together.
3. The wind-up doesn't move, but