EASY DOES IT
Grades 5-6

This lesson will provide students with an understanding of how inclined planes make work easier and the relationship between distance and force. The students will measure the force needed to move a model car a certain distance. The students will also measure the force needed to move a model car the same distance along an inclined plane. The students will make mathematical predictions based on the formula W = f x d and prove their predictions through experiments, demonstrating their knowledge of the distance and force relationship.

Simple Machines: Working Together (Coronet Films)
Bill Nye, The Science Guy: Simple Machines (KCTS/Seattle)

Students will be able to:

• demonstrate knowledge of the formula, W = d x f;
• compare the relationship between distance and force;
• compare hard work to the ease of work with simple machines.

Per Class:

• chart paper
• markers
• definitions with pictures

Per group of three:

• spring scale
• model car with detachable wheels
• box, height determined by teacher (9 in.)
• three inclined planes of various lengths (18, 36, 45 in)

Per student:

• worksheet
• pencil

• distance - a gap, space between two intervals
• force - the push or pull needed to move an object
• friction - resistance to motion
• inclined plane - a slanting or sloping surface used to raise an object to a higher level
• load - the object being lifted or moved by machine
• machine - any object that changes the force a person exerts on it
• work - when a pushing or pulling force moves something with weight through a distance

The vocabulary words will be written out with pictures to demonstrate the words. They will be placed around the room. Student volunteers will be asked to read each one. Students may volunteer some machines we use in everyday life.

The focus for viewing is a specific responsibility or task(s) students are responsible for during or after watching the video to focus or engage students' viewing attention.
Say, "Today we are going to learn about inclined planes, otherwise called ramps, that are a simple machine. We will learn how they work and how they help us to use less force." Say, "Can you see in the video two other machines that are inclined planes other than a ramp?"

BEGIN the video Simple Machines: Working Together immediately after opening credits showing a cartoon cave with a tree on the left. PAUSE the tape after narrator says, "but to scientists, work means something special." Ask if anyone can tell us what work is. (Use vocabulary definitions as a reminder if needed.) RESUME video, PAUSING after, "with all simple machines, the input work and the output work are equal, except for small losses through friction." Ask, "what is friction?" (Again, refer to vocabulary if needed.) Ask, "what kind of loss would you expect if there were no friction? What might happen?" RESUME the video and PAUSE after, "so for all simple machines the input force X and its distance are equal."

Write w = d x f on chart and review with students. Give examples such as: if w = 18, what could d x f equal? (9 x 2, 18 x 1, 3 x 6). RESUME the tape and PAUSE after "only their products have to be the same." Ask, "what is a product?" (The answer in multiplication.) Say, "so if I have a force of 3 pounds and a distance of 2 feet, what would my product be?" (Point out that answers must be in foot pounds, answer 6 ft. lbs.) Ask, "Can anyone give a different output force and distance to equal 6 ft. lbs.?" (accept 6 x 1 or 1 x 6) RESUME the tape. PAUSE after, "six times what equals 120?" (answer 20) RESUME tape and STOP after the caveman is knocking his head with his finger and says, "you can control the amount of the trade."

Change tape, insert Bill Nye, The Science Guy: Simple Machines. BEGIN the tape as Bill Nye slides down a fire pole and after reaching the bottom says, "using the fire pole is a fast and fun way to get down here, but using it to get back is another story." PAUSE after he says, "this is too much work." Ask, "what work is he talking about?" Help students relate this to the force needed to pull himself a distance up the pole. RESUME video and PAUSE after Bill Nye says, "we could use a ramp." Ask, "does anyone know what a ramp is?" Help students recognize it as an inclined plane. RESUME video and stop after the child's experiment with ramps and books as he says, "cool." STOP tape at the screen saying, "ramps equal less force." Ask if anyone can explain how ramps equal less force. Remind students to think about w = d x f.

Divide the class into groups of three. Pass out materials. Have the students attach the spring scale to the car and measure the force needed to lift the car straight up to the top of the box. Record the force needed and the distance lifted on the worksheet. Complete the formula w = d x f.

Experiment #2 worksheet: Using the shortest ramp, measure the ramp and fill in under "d" on the worksheet. Attach the spring scale to the model car and place the car at the end of the ramp as seen in the picture. Pull the car up the ramp to the top of the box. Record the force needed to pull the car up the ramp and enter it in the formula under "f." Complete the formula to find out how much work was needed to pull the car up the shortest ramp.

Experiment #3 is completed the same as #2 using the middle-sized ramp.

Experiment #4: Measure the longest ramp. Predict the force that will be needed to pull the car up the ramp. Test your prediction by pulling the car up the ramp following the same directions as Experiment #2 and #3.

Complete the questions included in the experiments.

Plan a neighborhood walk looking for inclined planes.

Have a car race using different length ramps, vs. different weighted cars and same distance ramps.

Invite a carpenter to discuss the construction and uses of ramps, and the formula used to determine the appropriate distance and angle of ramps.

Language Arts: Write a story of how the first use of a ramp came to be.

Math: Calculate what distance a ramp should cover for the force to be 1, 2, 3, 4 or 5 pounds for a work load of 60 ft. lbs. Make up other combinations. Given the work and distance, calculate the force. Given the work and force, calculate the distance.

Social Studies: Research the earliest inclined planes, people who used them, and the work they were doing.

Master Teacher: Mary Hanson

Click here to view the worksheet associated with this lesson.