Catchy Lesson Title



I want to be the Load!

Lesson Summary:

This lesson allows students to interactively experiment, as a class, with the three lever classes. Using students as the effort and the load, they find that repositioning the fulcrum can lead to remarkable results!

Subject:

• Science: Science as Inquiry, Physical Science

Grade Level:

• Target Grade: 7

• Upper Bound: 8

• Lower Bound: 6

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Time Required: 45 minutes

Learning Objectives:

• To understand the difference between 1st, 2nd, and 3rd class levers.

• To understand how the position of the fulcrum can change the ease in lifting the load.

• To have students actively involved in learning.

Prerequisites for this Lesson:

• An understanding of simple machines.

• An understanding of the concept of a lever.

Background & Concepts for Teachers:

• The teacher must understand the three lever classes:

o 1st Class: the fulcrum is in between the load and the effort.

o 2nd Class: the load is in between the fulcrum and the effort.

o 3rd Class: the effort is in between the fulcrum and the load.

• The teacher must also understand the following fundamental concept:

o It is easier to move the load when the fulcrum is closer to the load.

Activity Team/Group Size: Entire class

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Lesson Introduction / Motivation:

Have the students brainstorm different things that they believe are levers. The teacher may have a large chart at the front of the classroom on which he or she writes down all the items that students suggest.

Lesson Plan:

Arrange the classroom desks in a circle so that students are facing inward. Place the lumber and the scrap metal and the broom in the center of the classroom. The lumber will serve as the lever and the scrap metal as the fulcrum.

Begin by asking two different sized students to be your volunteers. Have one smaller student serve as the effort and the other one as the load. Start with the fulcrum farther from the load and ask the student who is the effort to try to lift the other student. This should be close to impossible. See the diagram below.

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Now, move the fulcrum farther from the effort (see diagram below) and ask the effort to lift the load. The student should be able to do this easily (maybe with just one finger!).

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Ask for another pair of volunteers to demonstrate 2nd class levers. Again, start with the fulcrum farther from the load and have the student who is the effort try and lift the person who is the load. When the students see that this is an incredibly difficult task, move the load closer to the fulcrum. Now, the student who is the effort should again easily be able to accomplish the task.

Finally, use the broom to demonstrate a 3rd class lever (without any student volunteers). Hold the broom at the top with one hand (the fulcrum) and use your other hand (the effort) to push the load (the bristled part of the broom). Explain how the effort you must exhaust varies when the fulcrum moves closer and farther from the load.

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Reusable Activity Cost Per Group [in dollars]:

• Broom—$8.00

• 2 ft x 8 ft piece of lumber—$10.00

• Piece of old Scrap Metal

• 3 Signs—one for “Fulcrum,” one for “Effort,” and one for “Load”

Lesson Closure:

After students have seen the explanation of the three lever classes explained above, the teacher may test the students’ understanding with a simple, yet active, follow-up activity. Have three signs: one that says “Effort,” one that says “Load,” and one that says “Fulcrum.” Ask for three student volunteers and give them each one of the signs. Ask them to create one of the classes of levers and successfully move the load. Whoever has the “Effort” sign serves as the effort, whoever has the “Load” sign serves as the load and whoever has the “Fulcrum” sign is in charge of positioning the fulcrum. If the students successfully create the class of lever assigned and lift the load, then they may pick the next three students. If they fail to do the assignment correctly, they must be given yet another lever class to create until they succeed. Encourage the other students in the class to help out. This way, the activity is more student-teaching-student rather than teacher-teaching-student.

Troubleshooting Tips:

When doing the Lesson Closure activity, make sure that every student participates. When students pick others to participate, ask them to pick only those who have not participated.

Assessment:

The Lesson Closure activity explained above provides an assessment technique that allows the teacher to know if his or her students adequately understood the material.

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Vocabulary / Definitions:

• Lever: a rigid bar pivoted about a fulcrum

• Fulcrum: the pivot about which a lever turns

• Effort: The point where you apply the force

• Load: The effect of applying this force

Lesson Extensions:

The lesson, Pulleys Pulling All Over the Place!, is an excellent follow-up activity to the levers lesson.

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Please email us your comments on this lesson:

E-mail to ljohnson@cvm.tamu.edu

Please include the title of the lesson, whether you are a teacher, resident scientist or college faculty and what grade you used it for.

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Keywords:

• Levers

• Simple Machines

• Fulcrum

• Load

• Effort

Authors:

Graduate Fellow Name: Marta Kobiela

Teacher Mentor Name: Shawn Martin

Date Submitted: 8-11-2005

Date Last Edited: 8-11-2005

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