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Gears

Name of Corresponding Unit Plan: Gear Uses

Grade Level: 2-8

VT Grade Expectations
VT S:21 Students demonstrate their understanding of Force by investigating variables that change an object's speed, direction, or both, and identifying and describing the forces that cause the change in motion.

NY Standards
NY Standard 1: Scientific Inquiry
Key Idea 1: Clarify ideas through reasoning, research, and discussion

Content Areas: Science

Recommended Length/Duration: 30-50 minutes

Learning Goals:

Students will understand how effort can be transferred between gears to increase power or speed.

Description/Sequence:

  1. The teacher should ask how many students ride a bicycle. Ask if they have one or many gears.
  2. Ask students to describe when they use different gears and what changing gears does for them.
  3. Describe the parts of the demonstration bicycle. Point out that on a bicycle the force is applied to the pedals to turn the wheels. The pedals are connected to the wheels by a chain that is driven by the gears.
  4. Beginning with a low gear, demonstrate that every time you turn the pedal once, the wheel will turn more than once.
  5. Shift to a higher gear. Count the number of times the wheel turns for each pedal turn. Repeat this for each of the gears.
  6. Point out that the gears on a bicycle are for either speed or power. We shift into a lower gear for more power to go up a hill and a higher gear for more speed. Changing gears allows us to pedal the same in different conditions.
  7. Ask students if they can think of other machines that have gears. Decide if the gears increase power or speed.

Materials/Resources: A bicycle turned upside down or on a bicycle stand.

Special Considerations: Students may have more or less experience with bicycles. Another gear train can be used for the demonstration, but bicycles are probably the common exposure to gears that most children have.

Extension: If students have many different kinds of bicycles you could ask them to analyze different gear trains. How are the bikes different? Why is each bike designed differently?