Lesson 1 - Wedge and Lever
Lab Packet: PDF | Open Office | Word Document
- Describe two of the simple machines, the wedge and the lever.
- Describe how each of these machines can make work easier.
- Represent data in a table and calculate the mechanical advantage.
- Construct a graph showing the relationship of force to effort.
- Make predictions using the data in the graph.
- Recognize examples of levers and wedges in their surroundings.
- Basic math skills.
- Graphing skills.
- Units of measure for force (Newton N), and distance (meter m).
- Basic vocabulary: force, work, fulcrum, lever, effort, resistance, wedge.
- Computer(s) with Internet connection and current Adobe Flash Player
- Calculator - there is likely one in the accessories panel in Windows or as a system tool on Macintosh.
- Student Lab Packet - This is a printable version of the lab materials (instructions, tables, and questions).
- For the Invitation To Learn: wedge-shaped door stop, paint can or other metal-topped container with an inset lid, coin, screwdriver, can opener (church key). For each pair or team of students: 10 pennies, a ruler and a pencil.
Challenge a student to hold a door shut against the efforts of another student to open it. Be sure to assign an appropriately assertive student to push the door open. Allow the holder to place one student desk in front of the door if they wish. After at least one failed attempt, provide the student holding the door with a wedge-shaped door stop to help. Discuss all results and ask for volunteered theories.
Present a closed paint can and/or other metal-topped container with an inset lid (powdered milk mixes, baking powder can), and ask someone to open one. Use fingers, a coin, scissors (careful, school scissors often break), screwdriver, can opener (church key). Take suggestions from the group for ways to open the can. Discuss the relative success of all methods. Ask for explanations of what did and didn't happen and why.
There are several terms with which students must be comfortable. Simple machines are first introduced in the primary grades. A reintroduction to the vocabulary could be accomplished by grouping students in fours, perhaps two sets of computer partners. Assign each student to demonstrate to their group the meanings of two of the vocabulary words. This gives each person a small but specific assignment and removes vocabulary from the realm of a paper/pencil activity.
Provide each pair or team of students with a ruler (lever arm), pencil (fulcrum), and about ten pennies or comparable weights. Challenge them to balance five pennies with five pennies, six with four, eight with 2, etc. Discuss relationships and adjustments made.
The questions asked in the Invitation To Learn should give a good assessment of where the students stand with their background knowledge.
One aspect not covered there is work. Perhaps generating a list of "What Is Work?" will give insight into their understanding of this concept. Each lab worksheet calls for prediction before completing the activity.
Directions for Teaching the Lab:
Each student should have a lab packet to record their data and responses. The lab contains guided labels which now correspond with labels in the lab. As they work through each activity, they will be prompted to discuss ideas with a partner. Each discussion area is labeled with this icon. Other options include Data Collection, Data Analysis, Graphing, Analysis Questions.
Invite students to proceed to the Student's Introduction (now the home page) where they will be introduced to simple machines, and the idea of Mechanical Advantage. Encourage discussion with their partners. Students are frequently asked to discuss their answers and predictions with their partner. Monitor this activity to help students share their ideas and value their partners as well. They should then return to the lab menu and proceed to the student lab.
As they enter the lesson 1, they are introduced to the problem of splitting large blocks of rock for use in construction. The simple machine used is a wedge. Work and mechanical advantage are not addressed here. They will experiment with wedges of various proportions to determine the most effective shapes and sizes. Encourage them to test a variety of shapes from very elongated to almost flat.
They will enter data on a chart and graph the wedge proportions and indicate where the effective shapes fall on the graph.
As they complete the questions about the wedge, they will scroll down to the activities related to levers. Use of complete sentences in answering questions is emphasized to insure students are able to express underlying ideas completely and to reinforce their understanding of the concepts. It is important that you discourage the use of single word or phrase answers.
The problem presented is to lift the cut stone onto a cart. Students are asked to state their knowledge of levers and work before proceeding.
They will test several levers by repositioning the fulcrum. Effort force and the distance through which it moves are recorded on a chart.
Using the data from the lever trials, students calculate work done and then the mechanical advantage.
This lesson will introduce students to the wedge and lever. They will be able to calculate work input, work output, and mechanical advantage.
Questions completed at the end of the activities will check the understanding of the basic concepts.
Challenge students to identify the fulcrum, placement and direction of both the effort force and the resistance force on a variety of levers such as:
- A broom (this will vary depending upon how the broom is used)
- Oar on a boat
- Bottle cap opener
- A coin used to open the battery compartment of a toy
- A prybar or a claw hammer
- A pole used to lift or move a rock
Assign students to keep record of the use of any wedge or lever they see for a day. Perhaps these could be listed on a bulletin board or on a simple machines "graffiti wall" within the classroom.
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