### Lisa MurpheySanta Rosa District Schools

#### Description

Students perform investigations to determine the combinations of lever and fulcrum placement to lift a weight most easily. They then assume the role of an archeologist with the task of moving a large rock from a dig site.

#### Objectives

The student understands the relationship between force and distance as it relates to simple machines (for example, levers and fulcrums working to lift objects).

#### Materials

-Common items that are levers to be used for demonstration (can opener, can, bottle opener, bottle, etc.)
-Long, narrow board for a lever, one per group of 4
-Triangular blocks for a fulcrum, one per group of 4
-Large rock, one per group (option-a stack of books can be used)
-Simple Machine Chart (See Associated File), one per student and one transparency
-Pencils
-Writing Journals or paper
-Writing Prompt (See Associated File), one per student

#### Preparations

1. Print out associated file documents, Simple Machine Chart and Writing Prompt.
2. Make one copy of each associated file per student.
3. Make a transparency of the Simple Machine Chart.
4. Collect examples of levers.
5. Collect boards, fulcrums, and rocks (or books).
6. Assign groups of 4 or 5 students.

#### Procedures

1. Distribute the Simple Machine Chart. (See Associated File) Tell students they are to put each simple machine listed into a category. Explain to students that this will not be graded. It is a tool for the teacher to determine what students already know. Students complete this assessment with no assistance. Discuss this assessment and put student answers on the transparency. Ask students why they chose the category. Guide them to correct any misconceptions. (See Assessments for Answers)

2. Demonstrate each example of a lever to the class. Explain that a lever has a fulcrum. The fulcrum is the point where the lever turns. Demonstrate the levers again. Ask, “Does each lever have a fulcrum?” (yes) “Can you always see the fulcrum?” (no)

3. Have a volunteer come to the front. Gently push the student. Ask students what you did. Have another student come forward and demonstrate pulling. Ask students what you did. Explain to students you were the force that moved each student. A force is a push or pull on an object that can cause it to start moving, speed up, slow down, stop, or change direction. Say, “We will use force to move an object using a lever.” Demonstrate how they will put their board on their fulcrum and how they can move the fulcrum to any location on the board.

4. Assign students into groups of 4 or 5. Give each group a board (lever), a fulcrum (triangular block), and a rock. Tell students they are going to determine where they should place the fulcrum under the board to lift the rock the highest. Have students put an H on the board where the fulcrum was placed for the highest lift. Next, tell students to move the fulcrum to see where the least force is needed to lift the rock. Mark this spot on the board with an E.

5. Have each group report and show the class where their H and E are on their board. Compare boards to see if the results were the same. If they were different, ask students why this is possible.

6. Have students return to their seats. Give them the Writing Prompt. (See Associated File) Review directions on the prompt with them and tell them these are the items which they need to include. Have them complete the assignment in their Writing Journal.

#### Assessments

DIAGNOSTIC ASSESSMENT (Simple Machine Chart):
Students list simple machines into the categories of lever, inclined plane, pulley, or wheel and axle. This assesses prior knowledge.
ANSWERS: Lever-pencil, screwdriver, balance, bottle opener, fishing rod;
Pulley-crane, reel;
Inclined Plane-screw, ramp, sliding board, toy car track;
Wheel and Axle-wheel, wheelbarrow.

FORMATIVE ASSESSMENT:
Students work in groups to experiment with levers and fulcrums to determine if fulcrum placement affects distance lifted and force needed. The teacher observes, questions, and comments to further understanding. Groups report on their results.

SUMMATIVE ASSESSMENT:
By responding to the Writing Prompt (See Associated File), students demonstrate understanding that fulcrum placement affects distance lifted and force needed.