Lesson Plan
Friction Isn't a Drag: It's a Force
Students will be able to use a model to show how friction is a force that opposes motion and is dependent on the types of surfaces in contact.
Understanding friction helps students explain everyday phenomena, from walking without slipping to why cars need brakes. It's a crucial concept in physics that affects almost everything around us.
Audience
7th Grade
Time
45 minutes
Approach
Hands-on investigation, guided discussion, and an interactive game.
Materials
- A Real Drag About Friction Slide Deck, - Friction Lab Investigation Sheet, - Friction in a Bag Sorting Game, - Assorted objects (e.g., wooden blocks, toy cars), - Various surfaces (e.g., sandpaper, felt, carpet, smooth tile, textbook), - Spring scales or rubber bands (for measuring force), and - Optional: Small weights to add to objects
Prep
Teacher Preparation
15 minutes
- Review the Friction Isn't a Drag: It's a Force Lesson Plan and all linked materials: A Real Drag About Friction Slide Deck, Friction Lab Investigation Sheet, and Friction in a Bag Sorting Game.
- Gather assorted objects (wooden blocks, toy cars, etc.), various surfaces (sandpaper, felt, carpet, smooth tile, a textbook), and spring scales or strong rubber bands for each student group.
- If desired, prepare small weights to add to objects during the lab.
- Set up stations for the Investigating Surfaces Lab activity.
Step 1
Introduction to Friction (10 minutes)
10 minutes
- Begin with the A Real Drag About Friction Slide Deck to introduce friction using the provided script and engage students with initial questions.
Step 2
Investigating Surfaces Lab (15 minutes)
15 minutes
- Distribute the Friction Lab Investigation Sheet to each student or group.
- Guide students through the lab stations, encouraging them to test different objects on various surfaces and record their observations and measurements of frictional force.
- Circulate and provide support, asking guiding questions about their observations.
Step 3
Analyzing Friction's Effects (10 minutes)
10 minutes
- Bring the class back together for a discussion.
- Use the A Real Drag About Friction Slide Deck to review key concepts from the lab.
- Discuss student findings from the Friction Lab Investigation Sheet, focusing on how surface texture impacts friction and how friction opposes motion.
- Ask students to share examples of friction they observed and discuss why some surfaces created more friction than others.
Step 4
Brainstorming Helpful vs. Hurtful Friction (10 minutes)
10 minutes
- Introduce the Friction in a Bag Sorting Game to conclude the lesson.
- Have students work in small groups to sort the examples into 'helpful' and 'hurtful' friction categories.
- Facilitate a brief class share-out of their sorting decisions and reasoning, reinforcing the real-world relevance of friction.
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Slide Deck
Friction Isn't a Drag: It's a Force!
Understanding the invisible force that affects everything around us!
Welcome students and introduce the exciting topic of friction! Ask them what they think friction is or where they've experienced it. Get them thinking!
What is Friction?
Friction is a force that opposes motion when two surfaces are in contact.
It tries to stop things from sliding or rolling past each other.
Explain that friction is a force that slows things down or prevents them from moving. Use simple, relatable examples like pushing a box across the floor or rubbing your hands together.
How Does Friction Work?
Even smooth surfaces have tiny bumps and grooves.
When two surfaces touch, these bumps can catch on each other, creating resistance.
Introduce the idea of microscopic bumps and grooves on surfaces. When these bumps catch, they create friction. Emphasize that all surfaces have some level of friction.
Surfaces Matter!
The texture of the surfaces in contact plays a huge role in how much friction there is.
Rougher surfaces generally create more friction.
Smoother surfaces generally create less friction.
Lead into the idea that different surfaces create different amounts of friction. This directly sets up the lab activity. Ask students to predict which surfaces might have more or less friction.
Friction's Force: Opposing Motion
Friction always works against the direction an object is moving or trying to move.
Think about trying to slide a heavy book across a carpet – it's tough because of friction!
Reiterate that friction always acts in the opposite direction of motion. If you push a box right, friction pulls it left. This is a key concept.
Friction's Other Side: Heat!
When objects rub together, the energy of their motion can be converted into heat.
Ever rubbed your hands together quickly? What happens?
Discuss how energy can be converted into heat due to friction. Rubbing hands is a great example. Mention other examples like brakes or meteor entry.
Time to Investigate!
Let's explore friction firsthand!
Today, you'll be experimenting with different surfaces and objects to see how friction changes.
Transition to the lab activity. Explain that students will be scientists investigating how different surfaces affect friction. Encourage careful observation and recording.
What Did We Discover?
Share your observations from the lab!
- Which surfaces created the most friction?
- Which created the least?
- What did you notice about the force needed to move objects on different surfaces?
After the lab, guide a discussion around their findings. Ask open-ended questions and prompt them to use evidence from their experiments.
Helpful or Hurtful Friction?
Friction isn't always good or bad; it depends on the situation!
Sometimes we want a lot of friction, and sometimes we want very little.
Introduce the idea that friction can be both helpful and harmful. This leads into the game where they'll sort examples.
Friction: An Everyday Force!
Friction is a powerful, invisible force that impacts our lives every single day.
Keep an eye out for friction in action!
Final slide to wrap up the lesson, reinforcing the main idea.
Worksheet
Friction Lab Investigation Sheet
Uncovering the Secrets of Friction!
Objective: To investigate how different surfaces affect the force of friction.
Materials You'll Use:
- Assorted objects (e.g., wooden blocks, toy cars, erasers)
- Various surfaces (e.g., sandpaper, felt, carpet, smooth tile, textbook)
- Spring scale or strong rubber band
- Optional: Small weights
Procedure:
- Choose an object: Select one object you will test on multiple surfaces.
- Attach the scale: Gently attach the spring scale (or rubber band) to your object.
- Select a surface: Place your object on one of the designated surfaces.
- Pull and Observe: Slowly and steadily pull the spring scale horizontally across the surface. Observe the reading on the scale just as the object starts to move, and as it continues to move. This reading represents the force needed to overcome friction.
- Record Data: Write down your observations and the force measured in the data table below.
- Repeat: Repeat steps 3-5 for all other available surfaces, using the same object.
- Test a new object (Optional): If time allows, choose a different object and repeat the entire process on the same surfaces.
Data Table:
| Surface Type | Object Used | Force to Start Motion (Newtons or relative units) | Force to Keep Moving (Newtons or relative units) | Observations (What did it look/feel like?) |
|---|---|---|---|---|
Analysis Questions:
- Which surface created the most friction? How do you know?
- Which surface created the least friction? How do you know?
- What did you notice about the force needed to start an object moving compared to the force needed to keep it moving? Why do you think this is?
- Based on your observations, how does the texture of a surface affect the amount of friction?
- How does friction oppose motion? Give an example from your lab.
Game
Friction in a Bag Sorting Game
Helpful or Hurtful? You Decide!
Objective: To identify and categorize real-world examples of friction as either helpful or hurtful.
How to Play:
- Work in your assigned groups.
- Your teacher will provide you with a "bag" (or list) of scenarios involving friction.
- As a group, discuss each scenario and decide if the friction described is Helpful or Hurtful in that particular situation.
- Sort the examples into two categories: "Helpful Friction" and "Hurtful Friction."
- Be prepared to explain why you placed each example in its chosen category.
Friction Scenarios to Sort:
- A. Rubbing your hands together to get warm.
- B. Car tires gripping the road.
- C. A rusty hinge on a door.
- D. Shoes slipping on ice.
- E. Brakes on a bicycle slowing you down.
- F. Air resistance slowing down a speeding bullet.
- G. Sandpaper smoothing a rough piece of wood.
- H. Gears in a machine wearing down over time.
- I. A rockslide caused by lack of friction.
- J. A match lighting when struck.
Group Discussion & Justification:
For each scenario, discuss and briefly note down why you categorized it as helpful or hurtful. Be ready to share your reasoning with the class!