4th Grade Motion Science

Summary

The lesson introduces motion and forces, then has students investigate how changing the force on a vehicle affects its movement.

Main Ideas

• Motion is a change in position.
• A force is a push or a pull that can start, stop, or change an object’s motion.
• Forces can come from different sources, including a person’s muscles, wind, or gravity.
• An object can remain at rest even while forces act on it. When forces are balanced, they cancel out and the object does not move. When forces are unequal, the resulting unbalanced force can make an object move.
• Students share competing predictions about a vehicle pulled by hanging weights. Some expect more weight to make it move faster or farther, while others think it may travel a shorter distance. The class investigates to find out.

Investigation: Testing a Falling-Weight System

Students work in groups to test how different hanging weights affect a vehicle’s motion.

1. Set up the workspace

   • Place the vehicle on a long, flat surface.
   • Arrange the cardboard and fishing line so the line connects to a hook at the vehicle’s front axle and hangs over the edge.
   • Place a bookend or similar barrier so the vehicle cannot fall off the surface.
   • Use a tape measure to measure how far the vehicle travels. Mark the starting position, such as the location of the back tires.

2. Run each trial

   • One student holds the vehicle in place while another adds the assigned washers to the hook.
   • On a signal, release the vehicle and observe what happens.
   • Do not give the vehicle an extra push, since that would affect the test. If it does not start, the directions allow a gentle touch to the back axle.
   • Repeat the activity for the different weight conditions.

3. Record observations

   • Write down what the vehicle did after each trial, including whether it started moving, how it moved, and how far it traveled.
   • Record observations before assigning speed rankings.
   • The worksheet includes a sample observation for one small washer: the vehicle initially did not move, then moved slowly.

4. Compare and rank

   • After all trials, compare the results and rank the conditions from 1 (slowest) to 5 (fastest).
   • Students may describe comparisons in their observations—for example, that one condition appeared faster or slower than another—but should wait until all tests are complete to assign rankings.

The teacher circulates to help groups set up the equipment, measure and record results, and follow the procedure. During cleanup, students return the vehicles, washers, line, and other materials to their buckets.

Speakers and Sources

• Teacher: The unnamed classroom teacher leading the lesson and explaining the concepts and procedure.
• Students: Jackson, Isaiah, Ramone, Preston, Drake, Isabelle, Ally, Ethan, Silva, Keeley, and Jaden, as named in the subtitles; other unnamed students also contribute.
• Written classroom materials: Science-journal instructions and a sample observation attributed to a fourth-grade observer.