# This is a well-developed lesson on the force of friction

Subject:

Science

4

Title – The Force of Friction
By – Erin Barnes
Primary Subject – Science

Unit Goal:

In this first lesson in a unit on motion and forces:

• Students will explain how friction works and how it relates to motion and force.
• Students will identify by experimenting whether a surface will have more or less friction.
• Students will explain where they might see friction at work each day.

Objectives:

Physical Science Processes and Inquiry:

PS1

2. Compare and/or contrast similar and/or different characteristics (e.g., color, shape, size, texture, sound, position, change) in a given set of objects, organisms or events.

PS3

1. Ask questions about the world and formulate an orderly plan to investigate a question.

2. Evaluate and design a scientific investigation.

3. Design and conduct a scientific investigation.

PS4

1. Report data using tables, line, bar, trend, and /or simple circle graphs

3. Make predictions based on patterns and experimental data.

PS5

3. Formulate a general statement to represent the data

Physical Science Content:

PS1

1. The position of objects can be changed by pushing or pulling. The size of the change is related to the push or pull.

Lesson Objectives:

• Students will conduct an experiment that shows how friction and surface texture can increase and decrease motion.
• Students will complete labs and show their predictions and results in a table.
• Students will explain how friction works and what results from friction.

Safety Considerations and Management Plan:

• Students could misuse materials in a dangerous manner. It is important that the teacher keep a good eye on the class to make sure everyone is using the equipment properly and safely.
• Tell students the consequences of bad choices in the classroom:
1. If student becomes a distraction or unruly give them a warning.
2. Upon the second infraction, remove the students from the experiment for 5 minutes.
3. If the child continues to act out, move them to a younger (K-2) classroom until the experiment is over.

Procedure:

1. Introduction/Set Induction:
• Ask the students who has heard of friction? What does it do? How does it work?
• Then discuss their prior knowledge of the topic.
• Ask the students to lightly place their hands together and rub their hands back and forth. As they are in the act of rubbing their hands back and forth, ask them to press their hands together harder and then even harder. Then ask, “What did you noticed?”
• Let students tell their newly developed characteristics and then explain to them that they just took witness to the forces of friction.
 The Force of Friction: Friction is the force resisting the relative motion of two surfaces in contact. When contacting surfaces move relative to each other, the friction between the two objects converts energy into thermal energy, or heat. Friction between solid objects is often referred to as dry friction or sliding friction and between a solid and a gas or liquid as fluid friction. A common way to reduce friction is by using a lubricant, such as oil, water, or grease, which is placed between the two surfaces, often dramatically lessening the coefficient of friction.
1. Instructional Procedures:

Activity:

Instruction:

• Students will be instructed to work through the following group activities in groups of three or four and record observations in their journals for later discussion.

• Students with hearing impairments will rely on written information to work through the labs.
• Students with learning disabilities will work collaboratively with groups.
• Tailor the activity to meet the special needs of specific IEPs.

Guided Practice:

Group work:

• Give students one matchbox car, one board, textbooks as stacking tools, a piece of rubber, a piece of felt, a piece of sandpaper and a stopwatch. Ask each group to record their findings as they work through all scenarios.
• They will start by stacking books and using the board as a ramp. They will start with the board alone and time the car from start to finish as it races down the board. They will need to repeat this three times and then find the mean time it took the car to go down the ramp.
• The students will repeat the process with the rubber placed on top of the board, then the felt, and finally the sandpaper.
• After discussing their findings, explain to them why their finding came out the way that they did. Explain that the amount of friction depends on surface material and force pressing objects together. The sandpaper was rougher and slower than the rubber piece. The greater the amount of friction, the harder/slower an object moves; the smaller the amount of friction, the faster/easier an object moves.

Guiding questions:

• What is it called when two objects rub together? (Friction)
• What makes the objects harder to rub together? (Resistance)
• What is one way to make it easier to rub two objects together? (Lubricants)
• What is produced by friction? (Heat)
2. Closure:

Students share data results taken during Guided Practice. Add or clarify information as needed.

 So What?!? Ask the students for real life examples of friction and how we use it and then provide them with the following information: There are many uses for friction. Why do we sand our streets in the icy conditions? (Streets are sanded to increase friction and help ensure safe driving.) Why does a skier or snowboarder use wax on his/her board? (They use wax to increase their speed, because every second counts in the Olympics!) How do we slow down or come to complete stops in our vehicles? (The brake pads use friction by rubbing together on the rotor to slow or stop the car.)
1. Independent Practice:

Activity:

• Students will individually summarize in their journals what they had discovered within their group experiments.
• They will also independently answer the following questions in their journals:
• Explain how friction works.
• Explain how heat is produced with friction
• What is sliding friction?
• What is one way to cut down the forces of friction? Give an example.

1. Evaluation/Assessment:

Formative:

• Monitor the group work to see if any students are having problems during the lab.
• If there are problems, assist students by asking questions related to their problems.
• Also ask them to think about why their results are coming out the way they are.

Summative:

• Collect the students’ journals and check for accuracy.
• Also assess the questions the students were asked to complete during the independent practice.
2. Resources and Materials:
3. Supplementary/Enrichment Activities:
• Find 4-5 keywords to define.
• Think of all the things you do on a daily basis, then choose an event or activity and answer the following:
• What two things are rubbing together?
• How is friction either helping or hurting in this case?
• If the friction is harmful, how can it be reduced? Or, if it’s helpful, what can be done to increase the friction?

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