Science · 3rd Grade · Forces, Motion, and Invisible Pushes · Weeks 1-9

Magnetic Attraction and Repulsion

Students will explore the properties of magnets, identifying materials that are attracted to them and observing magnetic fields.

• Common Core State Standards
• 3-PS2-3

About This Topic

Magnets are one of those topics students arrive knowing something about, but their knowledge is often incomplete or based on assumptions. This topic gives students a structured way to investigate what magnets actually do: attract certain materials, repel other magnets, and create a force that acts through space. NGSS 3-PS2-3 focuses on asking questions to determine cause and effect in magnetic interactions. Students sort materials as magnetic or non-magnetic, test the poles of two magnets, and observe how the force changes with distance.

The key vocabulary here becomes meaningful when students experience it physically. Discovering that two north poles push each other away while north and south pull together is far more memorable than reading it in a textbook. Students also learn to distinguish between "made of metal" and "is magnetic," a distinction that is commonly confused.

Active exploration is the most effective approach to the persistent misconceptions in this topic. When students test aluminum foil, copper wire, and iron nails side by side, the evidence they collect themselves is much more convincing than any explanation a teacher can give.

Key Questions

1. Differentiate between magnetic attraction and repulsion.
2. Analyze which materials are magnetic and which are not.
3. Construct a simple experiment to demonstrate magnetic force.

Learning Objectives

• Classify a variety of common objects as magnetic or non-magnetic based on experimental testing.
• Compare and contrast the interactions between different magnetic poles, identifying attraction and repulsion.
• Demonstrate how magnetic force can act through a barrier, such as a table or a piece of paper.
• Analyze the effect of distance on the strength of magnetic attraction and repulsion.
• Design and conduct a simple experiment to investigate a specific magnetic phenomenon.

Before You Start

Properties of Objects

Why: Students need to be familiar with identifying and describing the physical properties of different materials before classifying them as magnetic or non-magnetic.

Introduction to Forces

Why: Students should have a basic understanding of forces as pushes or pulls before exploring the specific force of magnetism.

Key Vocabulary

Magnet	An object that produces a magnetic field, which can attract or repel certain other objects.
Magnetic Field	The area around a magnet where its magnetic force can be detected. It is often visualized with iron filings.
Attraction	The force that pulls two magnetic objects, or a magnet and a magnetic material, towards each other.
Repulsion	The force that pushes two magnetic objects away from each other.
Pole	The ends of a magnet, typically labeled North and South, where the magnetic force is strongest.

Watch Out for These Misconceptions

Common Misconception

All metals are magnetic.

What to Teach Instead

Copper, aluminum, and gold are metals that are not magnetic. Hands-on testing with coins, aluminum foil, and iron nails gives students direct evidence to counter this assumption. The experience of a coin not sticking to a magnet is far more convincing than being told it won't.

Common Misconception

The bigger the magnet, the stronger it always is.

What to Teach Instead

Magnet strength depends on the material and type, not just size. A small neodymium magnet can outpull a large ceramic horseshoe magnet. Having students compare a small strong magnet to a large weak one makes this point directly.

Common Misconception

Magnets will attract any object if you get close enough.

What to Teach Instead

No amount of proximity will make a magnet attract plastic or wood. Students who bring a magnet right up to non-magnetic items and see nothing happen gain firsthand evidence that magnetic attraction depends on the material, not just the distance.

Active Learning Ideas

Inquiry Circle: Magnetic or Not?

Small groups receive a bag of 10 objects (paperclip, penny, rubber band, iron nail, aluminum foil, plastic button, etc.) and test each one with a bar magnet. They record results in a T-chart and draw conclusions about what makes something magnetic.

30 min·Small Groups

Gallery Walk: Pole Puzzles

Teacher sets up stations with two bar magnets at each, with the north and south ends unlabeled. Students try to figure out which ends are north and south based on attraction and repulsion behavior, then post their reasoning on a sticky note at each station.

25 min·Small Groups

Think-Pair-Share: The Distance Test

Pairs use a magnet and a paperclip to test how far the magnet can pull the clip through different numbers of paper pages. They discuss what happens to the force as distance increases and share their findings with the class.

20 min·Pairs

Real-World Connections

• Engineers use magnets in electric motors found in everyday appliances like blenders and fans, as well as in larger machines like trains and cars.
• Doctors use magnetic resonance imaging (MRI) machines, which employ powerful magnets to create detailed images of the inside of the human body for diagnosis.
• Recycling facilities use large electromagnets to separate magnetic metals like iron and steel from other waste materials for reuse.

Assessment Ideas

Exit Ticket

Provide students with a small collection of objects (e.g., paperclip, plastic toy, coin, iron nail, aluminum foil). Ask them to sort the objects into two groups: 'Magnetic' and 'Non-Magnetic', and write one sentence explaining how they decided.

Quick Check

Hold up two magnets. Ask students to predict what will happen when you bring specific poles together (e.g., North to North, North to South). Then, perform the action and ask students to explain the observed attraction or repulsion using the terms 'attraction' and 'repulsion'.

Discussion Prompt

Pose the question: 'How can you tell if something is magnetic without touching it?' Guide students to discuss the concept of a magnetic field and how it acts through space or barriers, referencing their experiments.

Frequently Asked Questions

What materials are magnetic?

Objects containing iron, nickel, or cobalt are magnetic. Most everyday magnets attract iron and steel. Coins (mostly zinc, copper, or nickel alloy), aluminum cans, and plastic are not magnetic, which often surprises students. Testing a variety of items is the clearest way to build this understanding.

Why do opposite poles attract and same poles repel?

At the 3rd grade level, it is enough to say that magnets have two ends with opposite 'personalities' called a north pole and a south pole. Opposites attract and matching poles push away. The full explanation involves magnetic fields and electron spin, which students explore in later grades.

How far can a magnet's force reach?

Magnetic force weakens rapidly with distance. A magnet that pulls a paper clip from 2 cm away may not pull it at all from 5 cm. Students can explore this by slowly increasing the distance between a magnet and a clip and recording the point at which the force disappears.

How can active learning help students understand magnetic forces?

Students arrive with strong pre-existing ideas about magnets, many of them wrong. Active sorting and testing activities create moments of genuine surprise, like discovering that a penny won't stick to a magnet. That kind of firsthand counterevidence is far more effective at shifting misconceptions than direct instruction alone.