Levers - Balancing
Name of Corresponding Unit Plan: Levers - Seesaw
Grade Level: K-8
Content Areas: Science
Recommended Length/Duration: 30-50 minutes
Primary – Students will discover that a lever can be balanced in a variety of ways. A longer lever requires a smaller weight to balance a heavier weight on a shorter lever.
Intermediate – Students will recognize the mathematical relationship between the length of the lever arm X the resistance weight.
- The teacher will describe the components of a lever system and how to set it up:
- Lever arm
- Resistance weights
- The teacher will explain the data that is to be recorded on the data collection worksheet.
- Students will work in groups or individually to create a variety of balancing systems.
- Students will record on their data sheet the weights and distance from the fulcrum for each side of the lever system.
- After testing a variety of systems, students should answer the questions on the worksheet.
- When groups are finished, the teacher should lead a discussion about their findings. Guiding questions might include:
- Did every system balance?
- Were you able to balance a heavy weight with a lighter weight?
- Were you able to balance a short lever arm with a long lever arm?
- What is the relationship between the length of the lever arm and weight?
- Is there a mathematical relationship between the length of the lever arms and weight in a balancing system?
- What other combinations would create balancing lever systems?
Materials/Resources Balancing Levers Worksheet (pdf); rigid rulers at least 30 cm long, a triangular or round fulcrum, a set of science weights or a collection of uniform objects (unifix cubes, sugar cubes, pennies, etc.)
Special Considerations It can be difficult to get a lever to balance exactly; close is generally close enough to make the point. Also levers should not swing too high from the desk top. A 30 cm wooden ruler balanced on a pencil is usually good. Be sure students read the measurement of the lever arm from the center of the weight. Older students should obtain data that will yield the formula: Weight 1 X Distance 1 = Weight 2 X Distance 2. This is the basic formula for finding the mechanical advantage of any lever system.