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Overview

In this lesson students will change the properties of a material by applying heat, and will see how the heat can rearrange atoms and change the material's physical shape. The shape's change generates force they can harness to run a simple machine, a lever.

Content Objectives

1. Students will describe and apply the following terms: first class lever, second class lever, third class lever, fulcrum, force.
2. Students will identify common levers in their classrooms.
3. Students will construct an actuator, a common application of the lever.

Grade Level: 6-8

Suggested Time

• Approximately 60-90 minutes, approximately 2 or 2.5 class periods

Process Objectives

1. Students will identify the terms lever, fulcrum and force. Students will be able to identify the three classes of levers: first class, second class and third class.
2. Students will apply the above terms while building an actuator.
3. Students will look at objects that they use in everyday life and identify the different types of levers.
4. Students will apply their observations to make predictions of new situations.
5. Students will experiment with the lever to observe new situations.

Assessment Strategies

1. Informal assessment during the background section through class discussion.
2. Pre-lab activity.
3. Completion of lever lab.
4. Completion of post-lab questions.

Media Resources

1. Levers, Actuators, and Exciting Materials Lab (MS) PDF Document

2. Levers, Actuators, and Exciting Materials Teacher's Guide PDF Document

3. Moving Atoms QuickTime Video (3 minutes 07 seconds)

Materials

• One piece of nitinol “muscle wire” about 18 cm long
• One spool of small gauge, uncoated copper wire (22 gauge or smaller)
• One package of n-size model train track connectors. You will want to cut them into their 1 cm long components. See the pictures of the connections for more information
• One 9V battery and connector
• One simple switch
• Two staples
• One paper fastener
• Three to six push pins
• One large piece of foamcore board
• One needle-nosed pliers
• Duct tape
• Scissors or a pen knife
• Ball bearing (optional)

Lesson: Levers

1. Introduce the topic of levers and assess background knowledge. What is a force and give some examples of forces. A force is a push or a pull and forces are exerted on objects everyday. Common examples of forces: kicking a soccer ball, throwing and hitting a baseball, pulling a sled, accelerating on a bicycle or a car. What is a simple machine? What is a lever?
2. Background. Use the background section of the Lever Lab to review and/or introduce levers.
   1. What is a lever?
   2. Describe the three types of levers.
   3. Give examples of the three types of levers.
3. Pre-lab: identifying levers. Using objects in the classroom, find examples of first, second and third class levers. Students will gather the objects and identify where the fulcrum, applied force and movement of each lever is. Have the students gather at least 2 examples of each type of lever.

Procedure: Lever Lab

1. Show the video and discuss: Moving Atoms QuickTime Video (3 minutes 07 seconds)
2. What are some concepts learned from the video?
3. Introduce the lab.
   1. Actuators are common examples of where simple machines such as levers can be found in the real world. An actuator is something that converts energy into motion. It can also be used to apply a force. An actuator typically is a mechanical device that takes energy, usually created by air, electricity, or liquid, and converts that into some kind of motion. That motion can be anything from blocking to clamping to ejecting. Actuators are typically used in manufacturing or industrial applications and may be used in things like motors, pumps, switches, and valves.
   2. A valve is a product rarely noticed by the average person, yet it plays an important role in the quality of our life. Each time you turn on a water faucet, use your dishwasher, turn on a gas range, or step on the accelerator of your car, you operate a valve. Without modern valve systems, there would be no fresh pure water or automatic heat in your home. There would be no public utilities, and beyond wood and coal, almost no energy of any kind. Plastics would be unheard of, as would many inexpensive consumer products. By definition, a valve is a device that controls the flow of a fluid. Today's valves can control not only the flow, but also the rate, the volume, the pressure or the direction of liquids, gases, slurries or dry materials through a pipeline, chute or similar passageway. They can turn on and turn off, regulate, modulate or isolate. They can range in size from a fraction of an inch to as large as 30 feet in diameter and can vary in complexity from a simple brass valve available at the local hardware store to a precision-designed, highly sophisticated coolant system control valve, made of an exotic metal alloy, in a nuclear reactor.
   3. The valve is one of the most basic and indispensable components of our modern technological society. It is essential to virtually all manufacturing processes and every energy production and supply system. Yet it is one of the oldest products known to man, with a history of thousands of years.
   4. In the lab, we will be using nitinol as the mechanism for the valve to open and close. Nitinol, also known as “memory wire,” is an alloy of nickel and titanium. Nitinol’s nickname, “memory wire” stems from its ability to regain its shape easily – it is a very durable and flexible substance! Nitinol is commonly used as a mechanism in the following:
      1. in braces as the wire that connects the brackets
      2. in a golf club insert
      3. in glasses frames to allow glasses to snap back to their original shape when bent
      4. in cell phones as a retractable antenna
   5. Nitinol will be used in the lab as the opening and closing mechanism.
4. Lab. Using the materials and the procedure on the Lever Lab, have the students complete the lab groups together in pairs (or groups of three).
5. Conclusions and Questions. Ask the students to complete their conclusions together, then lead a class discussion. See Teacher Answer Sheet for details:

   Levers, Actuators, and Exciting Materials Teacher's Guide PDF Document

6. Enrichment. Experiment with the lever you have built to come up with other scenarios.