# Lesson 12

Using a Trundle Wheel to Measure Distances

Let’s use our trundle wheels.

### 12.1: Measuring Distances with the Trundle Wheel

Earlier you made trundle wheels so that you can measure long distances.

If you do not have a trundle wheel, you can use an applet to simulate measuring. Your teacher will tell you a path whose distance you will measure.

• Measure the path with your trundle wheel three times and calculate the distance. Record your results in the table.

diameter number of rotations computation distance
trial 1
trial 2
trial 3
1. Decide what distance you will report to the class. Be prepared to explain your reasoning.
2. Compare this distance with the distance you measured the other day for this same path.
3. Compare your results with the results of two other groups. Express the differences between the measurements in terms of percentages.

To use the applet:

• Choose a diameter for the wheel, and enter a number 1 -- 5 for the path you will measure.
• Watch carefully to keep track of the number of rotations that the wheel makes before it stops.
• Try three different diameters for the same path, and compare your results.