#### Objectives

After investigating the work accomplished by applying force students will be able to:

1. Describe 2 of the simple machines, the screw and the wheel and axle.
2. Describe how each of these machines can make work easier.
3. Construct graphs showing relationships of measured data.
4. Make predictions using data on a graph.
5. Recognize use of these machines and the advantage of combining the screw and the wheel and axle.
6. Recognize relationship between the screw and the inclined plane.
7. Recognize relationship between the wheel and axle and the lever.
8. Recognize examples of the wheel and axle and the screw in their surroundings.

Preliminary Skills:

1. Graphing skills.
2. Units of measure for force, Newton (N), and distance, centimeter (cm).
3. These lessons build on basic concepts covered in Simple Machines Activity One and Activity Two.
4. Work = Force X Distance through which force moves.
5. Radius and circumference of a circle.

#### Materials

• Computer lab with Internet connections or a single machine and suitable projections equipment. We recommend a Pentium class computer (166 MHz, with at least 32 MB ram).
• Java-capable and enabled browser with the Java plug-in installed. For questions/assistance write:julie@cosmic.utah.edu
• Student Packet – This is a printable version of the lab materials. (Instructions, tables, graph formats and questions/problems) where students can record their lab.
• Invitation to learn:

An assortment of bolts and screws showing various thread density assortment of screwdrivers with a variety of handle sizes.

Examples of screws: screw on bottle caps, corkscrew, drill, auger, bolt driven scissor jack for cars, support jack screw.

Examples of wheel and axle: bike, clock, music box, toys with gears, etc.

Screws, nails and pieces of wood.

Rulers.

#### Invitation to Learn

To introduce the advantage of using a wheel and axle to increase force: provide a variety of screwdrivers with a range of handle sizes from the bulb shapes to the mini handles found in emergency kits. Give students two boards screwed together at convenient intervals and let them use various screwdrivers to remove and/or replace the screws. Discuss advantages and disadvantages of the different shapes.

You could add a little life to it by randomly assigning handle types and setting up a race.

Provide students with a variety of screws and bolts.

1. Ask them to group these objects and describe their categories. Let groups share their categories if no one recognizes thread density lead them to it.
2. Provide measurement tools (a ruler will do) and ask students to describe each item as completely as they can. Again, if idea of thread density is not discovered guide them to it.
##### To introduce advantages of the screw:

Stage a take off on the zip lock commercial. Provide a beverage container with a plastic pop on replacement cap and one with a screw cap, each half full, which one would they prefer to be vigorously shaken cap down over their homework, new jacket, head, etc?

Nail two pieces of wood together and attach two similar pieces of wood using a screw. Without using any tools ask students to take the two pieces apart. If they can turn the wood to apply leverage the nail should be more easily overcome. Be sure to use a nail and screw of comparable size.

##### Providing examples of each machine:

Identifying examples of the wheel and axle should not be difficult in our world of vehicles and gears. Perhaps you could bring in a bike, clock, music box, toy with gears, etc and have students identify the wheel and axles and identify the use of each: direction change, effort force applied to the wheel or to the axle.

Finding examples of screws used other than as fasteners is a little more difficult. The most common is the screw on lid. Other examples are corkscrew, drill, auger, scissor type jack found in many cars now is driven by a bolt, stationary jacks used to stabilize travel trailers frequently adjust to height with a screw, perhaps less accessible would be building jacks and supports used in construction.

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#### Lab Procedure

##### Directions for teaching the lab:

Each student should have a lab packet to record their data and responses.

Invite students to proceed to simple machine 3 lab activity where they are introduced to the use of a wheel and axle attached to a screw used to raise and lower an irrigation flood gate.

They look at a screw as a spiral inclined plane.

They are able to adjust thread density and compare effort force and distance lifted. These quantities are investigated by interpreting relationships shown by graphing these quantities.

Students are encouraged to discuss these relationships with their partner. Throughout the lab, students are called on to discuss outcomes and make predictions with their partners.

Monitor this activity to help students share their ideas and value their partner's ideas as well.

Use of complete sentences in answering questions is repeatedly 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.

Students are then lead to investigate the advantages of attaching a wheel to control the operation of the screw and predict the results of changing the radius of the wheel.

The applet allows students to adjust the wheel’s radius and record the effort force and distance lifted and then interpret these relationships through graphing the data.

The advantage of the wheel is explained through reviewing the lever

#### Closure

Students will receive a challenge at the end of the lesson to make three predictions of differing combinations of thread density and wheel diameters that will require the same effort force. There is also an additional challenge to create a Rube Goldberg device.

##### Extensions:

Students could create a display of various size screws and bolts classifying according to use, thread density, size etc. Challenge classes to find largest collection of screws.

Investigate Archimedes screw

"Invent" an ultimate screwdriver and hold a screwdriver derby.

Investigate irrigation flood gates used today.

#### Contact

Technical consultation and assistance is freely available to teachers and schools interested in using the ASPIRE website, on-line labs, and curriculum materials. In time, resources will be made available to assist schools lacking the computer technology required to access the labs. For technical assistance and resource information, please contact julie@cosmic.utah.edu

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