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What in the World is a Force?

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Lesson Plan

What in the World is a Force?

Students will be able to define force as a push or a pull and identify examples of contact and non-contact forces in everyday scenarios.

Understanding forces helps students explain why objects move, stop, or change direction, which is fundamental to understanding the physical world around them.

Audience

7th Grade

Time

45 minutes

Approach

Through direct instruction, guided practice, and interactive activities.

Materials

Whiteboard or projector, Forces in Our World Slide Deck, Objects for demonstration (e.g., ball, book, magnet), Construction paper or index cards, Markers, Scissors, Glue or tape, Push or Pull? Sorting Activity, and Identifying Forces Worksheet

Prep

Teacher Preparation

15 minutes

Step 1

Introduction to Forces (Warm-Up)

5 minutes

  • Begin by asking students: "What do you think of when you hear the word 'force'?" (2 minutes)
  • Project or write student responses on the board. (1 minute)
  • Introduce the lesson objective. (2 minutes)

Step 2

Defining Force: Push or Pull

10 minutes

  • Use the Forces in Our World Slide Deck (Slides 1-3) to introduce the definition of force as a push or a pull.
  • Demonstrate with a ball: push it, pull it (gently, with a string if available). Ask students to describe what you are doing.
  • Discuss different types of pushes and pulls (e.g., kicking a ball, opening a door, lifting a book). (5 minutes)
  • Lead a brief class discussion on examples of pushes and pulls they encounter daily. (5 minutes)

Step 3

Contact vs. Non-Contact Forces

10 minutes

  • Continue with the Forces in Our World Slide Deck (Slides 4-6) to introduce contact and non-contact forces.
  • Provide clear examples for each, using the demonstration objects (e.g., pushing a book is contact, a magnet attracting metal is non-contact).
  • Explain that contact forces require direct touch, while non-contact forces act from a distance.
  • Ask students to generate their own examples for each type. (5 minutes)

Step 4

Activity: Push or Pull? Sorting

15 minutes

  • Distribute the materials for the Push or Pull? Sorting Activity.
  • Explain the instructions: Students will sort various force scenarios into "Push," "Pull," "Contact Force," and "Non-Contact Force" categories.
  • Circulate to provide support and clarification. (10 minutes)
  • Review the activity as a class, discussing any discrepancies or interesting examples. (5 minutes)

Step 5

Worksheet: Identifying Forces

5 minutes

  • Distribute the Identifying Forces Worksheet as a cool-down or homework assignment.
  • Explain that students should complete the worksheet, applying what they've learned about defining forces and categorizing them.
  • Briefly review the first question to ensure understanding. (2 minutes)
  • Collect the worksheets at the end of class or at the beginning of the next session. (3 minutes)
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Slide Deck

What in the World is a Force?

Exploring the pushes and pulls that make things move!

Welcome students and introduce the topic of forces. Ask them what comes to mind when they hear the word 'force'. Record their ideas on the board.

What is a Force?

A force is simply a push or a pull that can make an object move, stop, or change direction.

Think about it:

  • How do you get a grocery cart to move? (Push it!)
  • How do you open a heavy door? (Pull it!)
  • How do you stop a ball rolling towards you? (Push it back!)

Explain that in science, a force is defined simply as a push or a pull. Give simple, clear examples like pushing a door or pulling a rope. Use a ball to demonstrate a push and a pull.

Pushes & Pulls Everywhere!

Let's think of some examples!

Pushes:

  • Kicking a soccer ball
  • Pushing a swing
  • Pressing a button

Pulls:

  • Opening a drawer
  • Tugging a dog's leash
  • Reeling in a fishing line

What other pushes and pulls do you experience today?

Have students brainstorm more examples of everyday pushes and pulls. Encourage them to think about sports, daily chores, and even playing.

Contact Forces

When objects touch each other to create a force, it's called a Contact Force.

Imagine you want to move a book across a desk. You have to touch the book to push it, right?

Examples:

  • Pushing a shopping cart
  • Kicking a football
  • Friction between your shoes and the ground

Introduce the concept of contact forces. Emphasize that there must be direct contact between the objects for the force to occur. Provide a few clear examples.

More Contact Force Fun!

Can you think of a time you applied a contact force today?

  • Pushing your chair under the desk
  • Pulling on a backpack strap
  • Hitting a baseball with a bat
  • The air resistance pushing on a parachute

Discuss more examples of contact forces. Ask students to share their own ideas and categorize them as pushes or pulls within the contact force type.

Non-Contact Forces

Forces can also act without objects touching! These are called Non-Contact Forces.

It's like magic, but it's science!

Examples:

  • Gravity: The Earth pulling you down
  • Magnetism: A magnet pulling on metal
  • Electrostatic Force: A balloon sticking to your hair after rubbing it

Now, introduce non-contact forces. Highlight that these forces act without direct touch, which can be a tricky concept for some. Use a magnet as a demonstration.

Mysterious Non-Contact Forces!

How do these forces work without touching?

  • Gravity makes objects fall to the ground, even from high up!
  • A magnet can attract or repel another magnet without touching it.
  • Have you ever seen static electricity make your hair stand on end? That's a non-contact force too!

Encourage students to consider how these forces are different from contact forces. Discuss the 'invisible' nature of non-contact forces.

Quick Check!

Is gravity a contact force or a non-contact force? Why?

Think about what we just learned... Does gravity need to touch something to pull it?

Conclude with a quick review question to check for understanding. This can lead into the sorting activity.

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Activity

Push or Pull? Sorting Activity

Objective: Students will categorize various scenarios as involving a "Push" or a "Pull," and then further classify them as "Contact Force" or "Non-Contact Force."

Materials:

  • Pre-made cards (or small slips of paper) with the scenarios listed below.
  • Four large labels or pieces of paper for sorting categories: "Push," "Pull," "Contact Force," "Non-Contact Force."

Instructions:

  1. Prepare Your Space: Clear a space on your desk or table. You will have four areas for sorting.
  2. Label Your Areas: Place the four labels (Push, Pull, Contact Force, Non-Contact Force) in separate areas.
  3. Read Each Scenario: Pick up one scenario card at a time and read it carefully.
  4. First Sort: Push or Pull? Decide if the scenario involves primarily a push or a pull. Place the card under the correct label.
  5. Second Sort: Contact or Non-Contact? After you have sorted all cards into Push or Pull, go through each card again. Now, decide if the force described is a contact force (requires touching) or a non-contact force (acts from a distance). You can make two sub-piles under each "Push" and "Pull" label, or write the type of force on the card if space allows.
  6. Discuss: Be ready to discuss your choices with your classmates and explain your reasoning.

Scenarios to Sort:

  • Kicking a soccer ball
  • Opening a refrigerator door
  • A magnet attracting a paperclip
  • Throwing a basketball
  • Sitting on a chair (gravity)
  • Pulling a wagon
  • Blowing out a candle
  • Jumping up and coming back down
  • Hitting a nail with a hammer
  • Combing your hair and a balloon sticking to it (static electricity)
  • Pushing a swing
  • Dragging a heavy box
  • A boat floating on water (buoyancy - hint: a push from the water)
  • Dropping a pencil
  • Pushing a button on a remote
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Worksheet

Identifying Forces Worksheet

Name: ____________________________

Date: ____________________________

Part 1: Defining Force

  1. In your own words, what is a force?


  2. What are the two main ways we describe a force?


Part 2: Push or Pull?

Read each scenario and decide if the force described is primarily a Push or a Pull. Circle your answer.

  1. You open a sliding door.
    Push / Pull


  2. You kick a football.
    Push / Pull


  3. You lift a heavy box off the floor.
    Push / Pull


  4. A car stopping when the brakes are applied.
    Push / Pull


  5. You row a boat through water.
    Push / Pull


Part 3: Contact or Non-Contact?

For each scenario below, identify if the force is a Contact Force or a Non-Contact Force. Explain your reasoning briefly.

  1. A book falling off a table.
    Type of Force: ____________________________
    Reasoning:





  2. You hit a baseball with a bat.
    Type of Force: ____________________________
    Reasoning:





  3. A refrigerator magnet holding a drawing to the fridge.
    Type of Force: ____________________________
    Reasoning:





  4. A person pushing a broken-down car.
    Type of Force: ____________________________
    Reasoning:





  5. A balloon rubbed on hair sticks to a wall.
    Type of Force: ____________________________
    Reasoning:





Challenge Question:

  1. Describe a situation in your daily life where you experience both a contact force and a non-contact force at the same time. Identify both forces.











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