# Friction: Friend or Foe? (SOL 4.2)

Teacher Name: Gemma Griffin
Grade Level: 4th
Subject: Science
Time Frame: 45 minutes
Concept: Energy; Force and Motion
Topic: Friction and Efficiency

## Rationale:

Students encounter friction in their lives on a daily basis. However, most children have not made a connection between daily activities, such as being able to walk without slipping, writing, stopping vehicles, and picking up and holding objects, and the important and necessary role friction plays. Efficiency is also relevant in life, as people strive to find effective ways to make work easier, such as using oil on moving parts of a bicycle, using soap to remove a ring stuck on a finger, using wheels or rollers to move heavy objects, etc. Students need hands-on experiences with material that is both interesting and familiar in order to make these important connections between science concepts and their own lives.

## Goals:

The student will work cooperatively in groups to conduct investigations.

The student will make connections between friction and the role it plays in every day activities.

The student will identify creating efficiency with reducing friction.

NSES Standards:

Science as Inquiry:

– abilities necessary to do scientific inquiry
– understandings about scientific inquiry

Physical Science:

– properties and changes of properties in matter

SOL’s: Science – 4.2 Force, Energy, and Motion

The student will investigate and understand that energy is needed to do work and that machines make work easier. Key concepts will include friction and efficiency.

## Objectives:

Cognitive:

The student will be able to identify and observe friction both orally and in writing, through the completion of four friction experiments and worksheet.

See attached checklist.

The student will be able to identify and observe efficiency, both orally and in writing, through the completion of four friction experiments and worksheet, as well as through the completion of one of two efficiency tasks. See attached checklist.

Affective:

The student will be able to connect the scientific concepts of friction and efficiency to real-life applications in their own life through oral discussion and manipulating familiar materials encountered daily through experimentation. See attached checklist.

Psychomotor:

The student will be able to create and investigate friction and efficiency, by physically conducting four friction experiments, and completing one of two efficiency tasks.

See attached checklist.

## Materials:

Smooth wooden board
Metal cookie sheet
2 toy cars
Shoes (smooth and rubber soled)
Eraser, crayon, ice cube, ping pong ball, rock
Small rubber ball, tennis ball
2 large bowls
water
4 books (approximately the same size and weight)
sandpaper, aluminum foil, plastic, wax paper

Advanced Organizer: (5 minutes)

Present the problem to the students – which wrapped book will be the hardest to pull, which will be the easiest to pull? (sandpaper, aluminum foil, plastic, wax paper) Have the students, as a group, order the wraps from the hardest to the easiest. Let the students touch the wrappings to get the “feel” of them. Students will then experiment with the materials to find the right order of the wrappings. Have students discuss their results and try to identify friction, record this tentative statement about friction on the board.

Procedures & Activities: (15 minutes)

1. Place students in heterogeneous pairs.
2. Explain to students the four different centers and materials available, which they will rotate through in pairs. The centers will be an opportunity for students to explore the causes and effects of friction in a hands-on manner.
3. Have students discuss with their partner and record in writing what they observed at each center.

Center #1 Toy Cars. Students will roll a toy car on the tile floor (or board) and then again on the carpet.

Center #2 Shoes. Students will slide on the floor with smooth soled shoos and rubber soled shoes.

Center #3 Wood vs. Metal. Students will place various materials (a rectangular eraser, crayon, ice cube, rock, ping pong ball, paperweight, etc.) on one end of a smooth rectangular piece of wood. Have students gently raise the board and discuss/record what happened to the objects on the board. This experiment should be repeated a second time using a metal cookie sheet, observations should be recorded as well.

Center #4 Water. Two bowls of water and one smooth rubber ball and one tennis ball will be provided. Students will test which ball will spin more easily in water.

4. Class Discussion (10 minutes). Have students discuss briefly their experiences with friction at the centers, and make observations and inferences about friction. (What happened with the smooth surfaces? rough surfaces? heavier objects v. lighter objects? sliding v. rolling friction of objects?)

Have students amend their previous generalization about friction, they may choose to add to, take away, or totally change their previous generalization on the basis of more information. Ideas they may have:

Smoother surfaces produce less friction, rolling friction produces less friction than sliding friction, and lubricants and streamlining reduce friction.

Friction is produced when the surfaces of two materials rub against one another.

Friction is the force that resists the movement, the force that causes things to stop moving.

The more friction, the harder it is to do work (i.e. the more friction, the less efficiency).

Friction can be helpful, as well as cause problems.

Have students brainstorm the usefulness and problems that can be associated with friction. For example, friction helps us walk without slipping (making rubber soled shoes more optimal than smooth ones). Friction though also causes carpet burns when we fall, fingernails squeaking on a chalkboard, keeps us from running faster, etc. Have students help brainstorm a list of pros and cons.

## Extension/Closure: (10 minutes)

Given what students understand now about work in relation to friction and efficiency, have students demonstrate this understanding by completing one of the two tasks in which they must increase or reduce friction to make the task more efficient. (5 minutes) Students may work in pairs or in small groups.

This extends students’ current knowledge to the idea that air creates friction as well, even though air is not a surface we can visibly see.

Efficiency tasks: choose one to complete

Using an object, which you are to pretend is very fragile, create a way to drop it from high, so that it will hit the ground with the least force.
Given a piece of paper, experiment with ways to manipulate it to cause it to go the greatest distance when thrown. (create a paper airplane, simply fold it in half, crumple it into a ball, etc.)
Have students share/demonstrate their solutions, and reasoning behind their solutions, with each other. (5 minutes)

## Differentiation:

This lesson will differentiate through learning style (kinesthetic, auditory, visual) as well as through varying learner levels, addressed through the heterogeneous pairing of classmates.

## Assessment/Evaluation:

See attached checklist (possible 24/24 pts for each student.)

Click here for supporting content about Friction.