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Friction In Our LivesFriction-In-Our-Lives

  • Subject: Physical Science
  • |
  • Grade(s): K-5
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  • Duration: Two class periods

Lesson Plan Sections


Students will understand the following:
1. Friction is a force that opposes motion, or makes it difficult for an object to move across a surface.
2. The amount of friction depends on the surface type and the force pressing two surfaces together.
3. Everyday life provides examples of how friction both helps and hinders everything we do.


For this lesson, you will need:
Several matchbox cars of the same size (three to four for every team)
Several large, thick books, such as encyclopedias (when stacked, they should be about 1 foot high)
Large piece of foam board
Beach towel
Masking tape
Chalkboard, overhead projector, or chart paper
Crayons, markers, colored pencils
Friction Activity Sheet (one for each student)


1. Create a learning web with your students on what stops motion. On an overhead, chalkboard, or chart paper write "Motion stops because . . ." and draw a circle around it. Elicit students' responses and write their responses as "branches" off of the web. Focus student responses by providing prompts, such as: What would make a car stop? A dancer? A football? A plane? A baseball player sliding into home?
2. Tell your students that the web they have created shows examples of forces that may slow down, stop, or make it hard for an object to move. Explain that these forces acting on objects and people are called friction. Refer back to the web and underline those ideas that clearly demonstrate the role that friction plays in stopping motion. Ask students in what context they have heard the word friction before. (They may offer the following contexts: friction between people in a fight or rubbing hands together.)
3. Explain to students that the amount or force of friction depends on two things: the type of surfaces that are touching (e.g., waxed kitchen floor versus rocky pavement) and the force pressing the surfaces together (e.g., pulling an empty wagon versus one filled with bricks).
4. Now divide the class into groups of four to five students. Explain to students that the following activity will help them understand how friction can be increased and decreased. Each group should receive three to four matchbox cars, foam board, a beach towel, masking tape, a yardstick, several large, thick books (that equal about a foot when stacked), two textbooks, and a Friction Activity Sheet. The groups will be observing and recording how the matchbox cars move on two surfaces: a smooth surface and rough surface.
5. Read the first activity question to the class: "Will the matchbox car move faster on the smooth surface or the rough surface?" Then show them the two surfaces they will be testing, the plain foam board and the beach towel.
6. Next, have students create a "ramp" by placing a stack of books (about 1 foot high) under one end of the foam board. (You may want to place a brick or heavy object at the other end to keep the board from sliding.)
7. Students will be looking at how a surface can effect car speed. In order to gauge the results of this activity accurately, they will need to use matchbox cars that travel at about the same speed. Have students "race" the matchbox cars they've been given down their ramp to find two that move at generally the same speed. To do this, line up the cars at the top of the ramp and hold them back with the yardstick. Have one student hold the yardstick at each end and lift it suddenly to let the cars race down the ramp. Do this a few times to make sure the two cars you select move at about the same speed
8. Now have each group cover the left-hand side of its foam board with the beach towel, using masking tape to secure the towel to the back of the board (to keep it from slipping). Their foam boards should now have two "tracks"—a plain track and a towel track.
9. Before students perform their race, have them complete the prediction portion of their activity sheets. Students should write one sentence indicating which surface they believe the car will travel faster on.
10. Now have the students race the two cars they chose (that were about the same speed). Using the yardstick to ensure the same "start time," have students race one car on the plain (smooth) track and the second on the towel (rough) track. They will need to write one to two sentences that describe how the two cars moved. Then have them determine on which surface they saw more friction.
11. Gather students together to discuss their findings and observations. Focus students' attention to the relationship between the surface type and the amount of friction there is between the car and surface, as demonstrated by the ability of the car to move across each surface. (The rougher the surface, the more friction there is.)
12. Read the second activity question to students: "Will it be easier to move one or two textbooks across your desk with your pinky?" Demonstrate how students will move the textbooks across their desks and have them complete the prediction section of their activity sheets. Remind students to record their observations on the activity sheet as they did in the first activity.
13. Gather students together to discuss the second activity. Ask students to share their observations. Encourage students to think about the relationship between the size/weight of an object and how easily it moves across a surface. Ask students if they needed to use more force from their pinkies to push two textbooks than just pushing one across the desk.
14. To reinforce the concepts demonstrated in the hands-on activities, on the board list the two factors that determine the amount of friction there is between two surfaces (surface type and force on a surface). Explain that friction plays many roles in our everyday lives. Sometimes we try to increase friction, while other times we try to decrease the amount of friction.
15. Use sports as a starting point to think of some examples. In some sports and recreational activities, you may want to increase or decrease the amount of friction present. Using what students have learned about surface type and force on the surface, create a T chart of sports and activities where increasing the amount of friction is helpful and those in which it is better to reduce the amount of friction. (For example: gymnasts use chalk on their hands to reduce friction between their hands and uneven bars; cleats help football players have better traction while running; bobsledders need to be light to travel faster in the Olympics; swimmers shave their arms and legs to increase their speed in races.)
16. Have students create a mini news article for a recreation or sports magazine about how friction plays a role in a sport of their choice. Students will need to include a colorful, creative picture of the sport in action and describe in a paragraph of four to six sentences how friction affects a player's performance in that sport. Have students present their articles and display them on the bulletin board. Physical education and health teachers can be invited to the class presentations.

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Adaptation for Younger Students:
Instead of having students complete the activity chart for the matchbox car and textbook activities, you can just have students observe and predict what they think will happen and share their ideas about the activities aloud. Also, this activity can be a teacher-led demonstration with student volunteers for the whole class. Rather than having students create an article about a sport, you can create a list of everyday activities where friction plays a role (e.g., snow boots on a slick sidewalk, brakes in a car, etc.) and have students create a book of illustrations titled Friction in Our Lives . Students can dictate descriptions of their pictures to an adult or older student.

Adaptation for Older Students:
For older students, you can explain the role of friction as an unbalanced force and how it relates to Newton's first law of motion—inertia. Students can use the Internet and other multimedia resources to create a slide-show presentation for the class about how friction and Newton's laws of motion play a role in sports. Have students design their own friction experiments and present their materials, procedure, data, and analysis in a written lab report.

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Discussion Questions

1. Explain how surface type influences the amount of friction there is.
2. Discuss the relationship between the size and weight of an object and the amount of friction that is present.
3. Analyze how friction can be both a positive and negative aspect in our everyday lives. Use examples to support your statements.
4. Sports such as soccer involve running, stopping, jumping, and kicking. Discuss how friction helps players.
5. Describe a situation in which using wheels would reduce friction between a moving object and the surface over which it travels.
6. Hypothesize what your life would be like if there were no friction. Which actions would be more difficult? Which would be easier?

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Assess students' understanding of concepts with a third friction activity similar to the ones done in class—with a question, prediction, observation, and analysis. For example, have students use a heavier toy car or truck to move across a rough surface (outside gravel, for example) and compare it with a lighter car moving on the same rough surface. Students should be able to explain that there is a lot of friction because of the rough surface, but a heavier/bigger car creates a larger force between the car and the rough surface, increasing the amount of friction.
In addition, a three-point rubric can be used to assess students' news articles about friction in sports:
  • Three points: includes a colorful, creative picture of the sport in action; explains what role friction plays in terms of helping or hindering the activity; discusses how friction is either increased or decreased by a surface type and by the force/mass of an object
  • Two points: displays minor misunderstandings in explaining friction's role and/or how to increase or decrease the amount of friction
  • One point: displays major misunderstandings of the role and/or how to increase or decrease friction

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Friction Forever Journal
Ask your students to keep a journal tracking all the activities they perform in one day where friction plays a role. Create a class list to see how friction will "forever" affect our lives.

Fords, Freights, Flights, & Friction
Invite your students to investigate the way friction is reduced or increased in various modes of transportation. Have them create miniature models of these machines and demonstrate to the class how friction plays an important role in motion.

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Suggested Readings

Planes and Other Aircraft: Learn the Science ? Build the Model
Nigel Hawkes, Alex Pang [Illustrator]. Millbrook Press, 1999
Using color artwork and photography this book explains the science of flight and how it translates into mechanical principals and aircraft design.

Eyewitness: Train (Dorling Kindersley Eyewitness Books)
John Coiley, Mike Dunning [Photographer]. DK Publishing, 2000
More than just a reference book, this offers striking color photography and rich content to describe how trains operate. It is a compelling book that traces the history of locomotives from the early steam trains to today's electromagnetic trains.

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Science Museum of Minnesota
The site features an excellent description of how ball bearings are used to reduce friction and improve motion.

Union Pacific Railroad Train Picture Archives
This Web site includes photographs of many trains, tracks, bridges, and so on.

Science Fun with Airplanes
At this site you'll find instructions with moving graphics on how to make a simple, powerful glider.

Hoopster Airplane (Exploratorium in San Francisco)
The site contains directions on how to improve on the jet engine model using a straw and two hoops.

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speaker    contact
Definition: A coming together or touching, as of objects or surfaces.
Context: When two surfaces are in contact, friction is always present.

speaker    drag
Definition: To pull along with difficulty or effort.
Context: An airplane comes to a stop because of the drag or pull on it as it moves through air and across a surface.

speaker    force
Definition: Strength or energy exerted.
Context: A force can change the direction of motion, increase the rate of motion, slow down motion, or stop it all together.

speaker    friction
Definition: The rubbing of one object or surface against another; the force that resists motion between bodies in contact.
Context: Bicycle brakes use friction to stop the wheels from turning.

speaker    motion
Definition: An act, process, or instance of changing place.
Context: A change in position of an object is a result of motion.

speaker    surface
Definition: The exterior or upper boundary of an object or body.
Context: The rougher an object's surface, the greater the amount of friction when another object moves against it.

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Grade level: 3-5
Subject area: Science
Understands motion and the principles that explain it.
Knows that when a force is applied to an object, the object either speeds up, slows down, or goes in a different direction.

Grade level: 3-5
Subject area: Science
Understands motion and the principles that explain it.
Knows the relationship between the strength of a force and its effect on an object (e.g., the greater the force, the greater the change in motion; the more massive the object, the smaller the effect of a given force).

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Tracy L. Coulson, middle school learning disabilities teacher, Fairfax County Public Schools, Fairfax County, Virginia.

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