Energy, Machines, and Motion
Part Two: Machines
Lesson 13: The Lever
Students apply their definition of a simple machine to decide whether a lever has the properties of a simple machine. In two inquires students will first explore how to position washers along a lever to balance a lever. In the second part of the lesson students will explore how the lever serves as a simple machine.
Focus Question: How do levers work? Why are levers machines?
3. Lesson Set-up and Management
EALR 2: Inquiry
Core content: Questioning and Investigating
6-8 INQC Collecting, analyzing, and displaying data are essential aspects of all investigations.
EALR 3: Application
Core content: Science, Technology, and Solving Problems
6-8 AAPD The process of technological design begins by defining a problem, identifying criteria for a successful solution, followed by research to better understand the problem, and brainstorming potential solutions.
- Students study the characteristics of levers by balancing loads along a lever.
- Students will determine the relationship between the effort force and effort distance on a lever.
3. Lesson Set-Up and Management
Materials:
- Students balance washers on each side of the lever. There are small variations in the weights of the washers, this will cause the lever to not be perfectly balanced. There are some suggestions in the teacher’s edition to minimize this effect. Students also understand that it is not a perfect system.
- In Inquiry 13.2 students position their spring scales upside down, make sure students calibrate their scale to reflect this difference.
- Students place a piece of masking tape on the pegboard for the load distance.
- Measuring the effort distance can be a bit tricky. Consider having students tape a ruler closer to where the effort force/distance is occurring.
Student Management:
- Students use a chart to record different ways washers will balance. After they have explored different possibilities students then need to form a rule. They may not notice the equations that form by multiplying the number of washers with the distance of the washers from the fulcrum. Try different question strategies to try to have students develop their own rules.
- Students can develop their own data table; this can lead to more
understanding of what data they will be recording. This also allows
students to generate more possibilities.
The Washers and the Lever
Left Side
Right Side
# of Washers
# of Holes
# of Washers
# of Holes
- Consider bringing in a long wooden plank and a block of wood that could serve as a fulcrum. Ask your students without them seeing these materials how the lightest/smallest student in the classroom could lift you up. Asking this question in advance could help set the stage for the idea of a lever.
- Ask your students about experiences they have had with a teeter-totter to bring out their personal experiences with levers.
Writing Support:
- Students are asked to draw a picture of something that balances and how to get a rock out of the ground. Ask students to add labels to their drawings.
- Students can paste in different examples of different classes of
levers into their notebook, along with examples of different tools
that fall into each class of levers. The following notebook entry
depicts information from the Enchanted Learning website.
Reading Support:
- There are two reading selections at the end of the lesson.
- The first reading, “Understanding Levers As Easy As 1-2-3,” gives students examples of the three classes of levers.
- The second reading, “Alexander Calder Making Art Move,” shows how physical principles can be put to use in works of art.
Math Support:
- N/A