Science · Grade 3 · Invisible Forces: Magnetic and Static · Term 1

Exploring Magnetic Poles

Students will investigate the properties of magnetic poles and how they interact (attract or repel) with other magnets.

• Ontario Curriculum Expectations
• 3-PS2-3

About This Topic

Magnetic interactions introduce Grade 3 students to the concept of non-contact forces. Students explore how magnets can pull (attract) or push (repel) objects without touching them, and they identify which materials are magnetic. In Ontario, this topic connects to practical applications like compasses and household tools. It encourages students to think about 'invisible' forces that govern the physical world around them.

By testing different materials and observing how magnetic fields work, students develop their inquiry and prediction skills. They learn that magnetism is not just a 'magic' trick but a predictable force with specific rules. This topic particularly benefits from hands-on, student-centered approaches where learners can test their own hypotheses and discover the properties of magnets through trial and error.

Key Questions

1. Predict the interaction between two magnets based on their poles.
2. Explain why some materials are attracted to magnets and others are not.
3. Design an experiment to test the strength of different magnets.

Learning Objectives

• Classify objects as magnetic or non-magnetic based on experimental results.
• Compare the attractive and repulsive forces between magnets with like and unlike poles.
• Predict the interaction between two magnets based on the orientation of their poles.
• Design and conduct an experiment to test the strength of different magnets.
• Explain why certain materials are attracted to magnets and others are not.

Before You Start

Properties of Objects

Why: Students need to be familiar with observing and describing the physical characteristics of objects before investigating their magnetic properties.

Forces and Motion

Why: Understanding that forces can cause objects to move or change direction is foundational to grasping magnetic attraction and repulsion.

Key Vocabulary

Magnet	An object that produces a magnetic field, causing a force that attracts or repels other magnetic materials.
Magnetic Pole	The two ends of a magnet, typically called North and South, where the magnetic force is strongest.
Attract	The force that pulls two magnets or a magnet and a magnetic material together, occurring between opposite poles (North and South).
Repel	The force that pushes two magnets apart, occurring between like poles (North and North, or South and South).
Magnetic Field	The area around a magnet where its magnetic force can be detected.

Watch Out for These Misconceptions

Common Misconception

All metals are magnetic.

What to Teach Instead

Many students think anything shiny or metallic will stick to a magnet. A hands-on sorting task with copper pennies, aluminum foil, and steel nails helps them discover that only certain metals (like iron, nickel, and cobalt) are magnetic.

Common Misconception

Magnets only work through air.

What to Teach Instead

Students often believe a barrier will stop a magnet. Testing magnets through water, paper, or plastic during a station rotation proves that magnetic forces can pass through many non-magnetic materials.

Active Learning Ideas

Stations Rotation: Magnetic Explorers

Set up stations where students test which classroom objects are magnetic, use iron filings to see invisible magnetic fields, and try to move a paperclip through a table using a magnet underneath.

50 min·Small Groups

Simulation Game: Human Magnets

Students wear 'North' or 'South' labels. They move around the room and must try to 'connect' with others; if they meet a matching pole, they must push away, but if they meet an opposite pole, they link arms.

20 min·Whole Class

Inquiry Circle: The Floating Paperclip

Groups are challenged to make a paperclip 'hover' in the air using a magnet and string. They must experiment with the distance between the magnet and the clip to find the 'sweet spot' of the magnetic field.

30 min·Small Groups

Real-World Connections

• Engineers use magnets in electric motors for appliances like blenders and washing machines, as well as in speakers for stereos and televisions.
• Navigators have used magnetic compasses for centuries to determine direction, relying on Earth's natural magnetic field to guide ships and explorers.
• Recycling facilities use powerful electromagnets to separate ferrous metals, such as iron and steel, from other waste materials for reuse.

Assessment Ideas

Exit Ticket

Provide students with two bar magnets. Ask them to draw how they would orient the magnets to make them attract and then how they would orient them to make them repel. They should label the poles in their drawings.

Quick Check

Hold up a collection of objects (e.g., paperclip, plastic toy, coin, wooden block, iron nail). Ask students to predict which objects will be attracted to a magnet and then test their predictions. Record results in a simple T-chart: Magnetic / Not Magnetic.

Discussion Prompt

Pose the question: 'Imagine you have three magnets, but their poles are not labeled. How could you design a simple experiment to figure out which pole is North and which is South on each magnet?' Facilitate a class discussion on their proposed methods.

Frequently Asked Questions

What are the best types of magnets for Grade 3?

Strong ceramic bar magnets or horseshoe magnets are best. They clearly show the North and South poles, which is essential for teaching attraction and repulsion. Avoid small button magnets as they can be a safety hazard.

How do magnets relate to the Earth?

The Earth acts like a giant magnet with its own magnetic field. This is why compasses work. You can explain that the needle of a compass is a small magnet that aligns with the Earth's magnetic poles to help people find their way.

How can active learning help students understand magnetic forces?

Since magnetic forces are invisible, students need to 'feel' the push and pull to believe it. Active learning allows them to experience the resistance of two North poles repelling, which creates a much stronger mental model than just reading about it.

Are there any Indigenous connections to magnetism?

While magnetism is a physical science concept, you can discuss how Indigenous navigators used the stars and natural landmarks for travel, and how the introduction of the magnetic compass changed navigation in Canada's history.