Materials (per student)
Leading the Activity
Have a pair of scissors safely located, but visible in the classroom. Involve students in a discussion of the components of a lever, and how those components are arranged in a first class lever. Ask student groups to discuss how a double first class lever might look. Encourage them to think of an example of a double first class lever. Invite student groups to share their ideas. Share with students that there is an example of a first class lever in the classroom. Challenge them to find the example. Involve students in a discussion of how the scissors are constructed and how the scissors work. Explain that they will be doing a double first class lever search at home. Discuss the procedures with the students, and safety issues.
Procedure
- Find as many double first class levers at home as you can.
- Observe each double first class lever carefully.
- Draw a picture of the double first class lever.
- Identify on the drawing the fulcrum, the arm, the place at which force (effort) is applied, and the place at which the load is located.
- Write a description of how this simple machine works and how it is used.
Optional: Bring an example of a double first class lever to share in the classroom. (Remind students that parent permission might be required.)
Teacher Background Information
Some tools are made of double first class levers where two lever arms share the same fulcrum, or pivot point. Examples of double first class levers that students may find at home or in a tool box include garden shears, wire cutters, pliers, spring clothespins, center-hinged salad-serving utensils, and forceps with handles.
Students should be reminded of the safety precautions involved with handling sharp objects. Since this is a home assignment, parents might be invited to look for and investigate the double first class lever tools with the students. Parent permission might be required for the students to bring in an example of the double first class lever.
