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University of Nebraska–Lincoln

Transportation Systems Engineering

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Lesson Overview
Lesson Title:
Clever Levers

Teachers:
Mr. Jesse Andres (Primary)

Brief Description:
This lesson will introduce a lever as one type of simple machine. Students will learn about the parts of a lever and how it can achieve mechanical advantage.

Topics Introduced:
Mechanical advantage

Transportation, Distribution, and Logistics Curriculum Framework Components Addressed:
Facility and Mobile Equipment Maintenance
Suggested Grade Levels:
7th Grade
8th Grade

Subjects:
Science
Standards Taught:
8.3.3 Science 2003

Lesson Information
Learning Expectations:

Students will be able to identify the fulcrum of several examples of levers.
Students will demonstrate the relationship between mechanical advantage and relative distance between the load and effort.
Students will apply this relationship to a conventional example of a lever.

Plan Of Action:

1. Lever introduction and definition:
a. Candle-light teeter totter demonstration. This is a lever with candle sticks at each end. Once the candles are lit, the weight of each of the candles changes at different rates because the wax drips off. This put the lever off balance and in motion, first rocking back and forth and possibly moving in a complete circle.

This activity takes about 8 minutes to get going to achieve the full effect. In the mean time I will provide the following definition. A lever is a stick or bar that pivots or moves about a point. The point at which the lever moves is called a fulcrum. I will also talk about the forces involved.

The following activities are things to do while the candle light teeter totter is in action.
a. Student activity: Identify the fulcrum in several examples of levers.
i.) Pry bar, hammer, paddle, bat, foot pry, scissors, bike brake

c. Pre-quiz

2. Mechanical advantage (leverage) of a lever demonstration. In this demonstration I will use a lever to balance two bowling pins with one bowling pin. I will add more bowling pins to the load and move the single bowling pin out on the effort arm. I will do this until I demonstrate 7 pins held up by 1.

3. Student activity: Lever lab
Students will place the meter stick across the table with cm side up. Place a pencil under 50 cm mark of the meter stick. The pencil will be the fulcrum. Students will balance the lever system by placing one penny on opposite ends of the meter stick. Students will record the distance of each single penny from the fulcrum in the data table for the 1st challenge. Students will repeat step 2 except balance 4 pennies with 1 penny for the 2nd challenge. Finally students will repeat step 2 except balance 10 pennies with 1 penny for the 3rd Challenge.

4. Thinking like engineers extension activity: Werner transportation semi truck trailer lever extension activity.
Students will consider the load bearing force applied to the fulcrum. The rear axles of a semi trailer will be the load bearing fulcrum. Students will experiment with changing the location of the load and see how it effects the force on the fulcrum (rear axles). Students will also change the location of the axles and see how this effects the force applied to the axles. Students will do this by using an 8 foot plank set on top of two force plates. The reading of the force plates will be projected using lab pro technology. Student will center their weight by walking on the plank until the force plates show an equal reading. Students will mark those locations; I will move the force plates representing the axles of a semi trailer. Students assume the their locations on the plank again and see the difference in force applied to the force plates.

5. Clever lever: The clever lever is a teeter totter with a round fulcrum and an 8 foot plank. Two force plates will be located on each end of the plank. One student will sit on one force plate and another will push down on the other plate. The clever lever can then be moved horizontally rolling on the fulcrum. The changes in the mechanical advantage can be graphed and projected in real time using lap pro technology.


Data Set Used:

Student will collect data on the distance required to balance a lever with a mechanical advantage of 1, 4 and 10.

Materials Needed:

1. Candle light lever demonstration: candles and lever
2. Identify the fulcrum activity: examples of lever, pry bar, hockey stick, scissors, etc…
3. Lever lab activity: Meter sticks, pennies, and pencils
4. Extension activity: computer, labpro interface, two force plates, and one plank


Preparation Period:

The construction of the candlestick teeter totter, and clever lever demonstrations takes about one hour to build and set up. The lever lab takes 20 minutes to set up.

Implementation Period:

two days

Science, Math, Engineering and / or Technology Implications:

Thinking like engineers extension activity: Werner transportation semi-truck trailer lever extension activity.
Students will consider the load bearing force applied to the fulcrum. The rear axles of a semi trailer will be the load bearing fulcrum. Students will experiment with changing the location of the load and see how it effects the force on the fulcrum (rear axles). Students will also change the location of the axles and see how this effects the force applied to the axles. Students will do this by using an 8 foot plank set on top of two force plates. The reading of the force plates will be projected using lab pro technology. Students will center their weight by walking on the plank until the force plates show an equal reading. Students will mark those locations; I will move the force plates representing the axles of a semi-trailer. Students assume their locations on the plank again and see the difference in force applied to the force plates.

Unexpected Results:

It may take more time.

Considerations for Diversity in Education:

The lab activity is hands-on and will allow students to work in groups. The demonstrations are engaging to the unmotivated learner and the visual learner.


Lesson Files
Lever Prequiz and lab activity
The front side is a prequiz on levers and the back is the lever lab worksheet.
[size: 166400] [date uploaded: Mar 27, 2010, 6:33 am ]

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