# 02Exploring magnets

Mf02TA of the Motion and force topic
• ## 01 Selecting and developing activitiesMf02TAnugget01 Suggestions

### Based on the Physics Narrative and the Teaching and Learning Issues

Ideas to emphasise here

• one thing acts on another without touching it
• the physical experience of feeling the interactions between magnets, or between a magnetic material and a magnet
• distinguishing between a permanent magnet, and magnetic materials
• magnets have two different ends, which we call North or South poles
• no matter how small you cut a magnet you always have two poles
• like poles (South and South or North and North) repel each other
• different poles (South and North or North and South) attract each other
• a few, but not all, metals are attracted to magnets. These metals are iron, cobalt, nickel or their alloys – like steel
• you can make a new magnet by stroking an existing magnet on a piece of iron

Teacher Tip: Work through the Physics Narrative to find these lines of thinking worked out and then look in the Teaching Approaches for some examples of activities.

Strategies for supporting learning

• distinguish action at a distance from action by contact
• build a way of thinking about permanent magnets that supports children being able to make predictions
• having in mind an explicit model of permanent magnets
• root your approach in the phenomena; a full theory of magnets is very complex
• being consistent in the drawing of force arrows
• use a sequence that encourages children to formulate ideas about an unseen force

Teacher Tip: These are all related to findings about children's ideas from research. The teaching activities will provide some suggestions. So will colleagues, near and far.

Avoid these

• conflating magnetic and gravitational effects – more easily done than you might expect as both are action-at-a-distance forces
• suggesting that gravity is a magnetic effect
• presenting magnetism as a series of unlinked effects

Teacher Tip: These difficulties are distilled from: the research findings; the practice of well-connected teachers with expertise; issues intrinsic to representing the physics well.

• ## 02 A sequence to develop ideas about magnetsMf02TAnugget02 Sequence

### Based on the Physics Narrative and the Teaching and Learning Issues

Meeting reality: valuable experiences

Magnetism is mysterious because we cannot see what is causing the force, we can only see its effects. Clearly it has links to work on forces and the idea of action-at-a-distance. However care must be taken as children mix up these ideas.

• seeing that magnets can attract certain metals
• experiencing both attraction and repulsion; push and pull
• seeing that two different kinds of poles exist
• experiencing that magnets tend to be stronger at their poles
• making a magnet by stroking an iron nail with a permanent magnet, so aligning mini-magnets in the nail

Teacher Tip: As many of these as possible should be direct physical experiences, rather than mediated through video clips. This locates the learning in the lived-in world of the child, and grounds the learning in specific physical circumstances.

A sequence for developing the idea

This is a short sequence, designed to leave children questioning, intrigued, and perhaps a little surprised. It is all too easy to go too far, and we'd suggest avoiding any measurements with newton meters, any mention of magnetic fields, and any work with iron filings. Rather children should be exploring physical phenomena of permanent magnets with their own hands. Magnetism, although complex to explain, is a wonderfully tactile experience of action without contact, or action-at-a-distance. The force of gravity and the electrical force, which are also action-at-a-distance forces, are much less amenable to child-scale manipulation.

Teacher Tip: The ideas are developed in the Physics Narrative.

What can a magnet do?

Here children explore action at a distance

Exploring magnetic poles

You can use this activity to introduce the idea of a magnetic pole, and see how to magnetic poles interact.

Hanging with magnetism!

This demonstration is useful for introducing the idea of action at a distance

Magnet strength and action at a distance

This small investigation is useful for beginning to quantify the actions of a magnet and perhaps for exploring the idea of making reasonable deductions from evidence, given a good experimental design.

Researching the Earth's magnetism

This is a possible research activity, focusing on some of the effects that rely on the Earth's magnetism rather than on the magnetism itself.

Finding north

This is a demonstration-supported discussion that introduces the idea of a North Pole as a north-seeking pole.

Messages from research and practice: specific tripwires for this idea

Exploring the action of magnets is a good context within which to begin to experience and think about action at a distance. Because this does not involve contact unlike many of the forces already met, it is an area with some difficulties.

Which are magnetic?

Every object is more or less magnetic, but we commonly distinguish those which have a strong response to magnets as being magnetic. In particular some metals are identified as magnetic, and this challenge outlines some of the difficulties in performing that classification.

Magnetism and gravity

Magnetic and gravitational effects are often conflated and this challenged spells out some of the reasons why and give some strategies for avoiding that conflation.

Teacher Tip: These challenges and some suggestions for working with them are more fully explained in the Teaching and Learning Issues.

Representing and reasoning: doing physics

Introducing children to magnets should be a largely phenomenal affair: lots of exploring, lots of interest and excitement. There will be opportunities for reasoning about magnets, and what to expect, but we do not think it will be wise to develop a theory of magnets. The model of magnets, which will be introduced at the next stage, is there to guide the explorations that you might suggest.

Magnets everywhere

Everything is more or less magnetic and you will find magnets in all kinds of locations and devices. you will need to be aware of the multiple locations and the graduation in what it is to call something magnetic.

The poles of a magnet

The idea of a magnetic pole is seemingly simple, but can lead to complications if not dealt with carefully.

Interactions between magnets

There are very simple rules, but the rationale behind these rules is not so simple. In fact one general rule is not really available until after you have met magnetic field lines: so a simple approach based on empirically derived rules is suggested.

A model of magnets

This is something to bear in mind, and perhaps the having the back of your mind when you're having conversations with children, rather than aiming to communicate this quite sophisticated model to all children.

• all materials are more or less magnetic
• the actions of a permanent magnet are concentrated at its magnetic poles
• repulsion or attraction can occur between two magnets
• permanent magnets may obviously attract some materials – these are commonly called magnetic

Teacher Tip: Find out more from the Physics Narrative.

• ## 03 What can a magnet do?Mf02TAnugget03 Activity

### Exploring what you can do with a magnet

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

This is a simple hands-on exploration of what magnets do, allowing for surprise and delight. Experience suggests that it'll be crucial to focus on whether the children think magnets attract all metals, or only some metals.

What to prepare

• a magnet
• a set of objects, as representatives of different materials (eg: string, paper, paper clips, copper coins)

Here are some suggestions for everyday objects made of different metals.

• iron and steel: nails and screws
• stainless steel: some kitchen sinks, cutlery
• brass: screws
• zinc: battery case
• copper: old pennies, copper pipes
• bronze: some marine fittings
• aluminium: kitchen foil
• silver: expensive silverware, some jewellery
• gold: wedding rings!
• mercury: thermometer
• nickel: some coins

What happens during this activity

Ask the students to investigate what can and cannot be picked up by a magnet. Ask them to predict which of the objects in front of them will be able to be picked up.

As an extension you may want to start off with asking children to list everywhere they have magnets in their house. Based on experience they will list places where they are more obvious – like on the â€˜fridge or on magnetic latches, rather than in other devices, microphones and speakers for example (We'd suggest not deliberately introducing electromagnetic devices such as audiovisual equipment or electrical motors.)

You might also have to hand a supply of coins from different countries: some contain magnetic metals, some do not.

• ## 04 Exploring magnetic polesMf02TAnugget04 Activity

### Poles: more than coloured ends

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

Most school magnets have brightly coloured poles, often red and blue, sometimes red and black.

Here children are exploring how these marked poles affect each other.

What to prepare

• a pair of bar magnets with coloured poles

What happens during this activity

Ask the children to investigate what happens when the colours are brought together. Red to red, blue to blue, red to blue and so on.

Encourage them to be systematic and to record their results in such a way that it'll be possible to check that the different groups agree. You might like to prepare a large shared chart on which all results can be recorded. Matters of public agreement and record are important in the sciences, and this is a good opportunity to establish that.

Suggest that children extract and express a pattern from their results. This is an important process in the sciences: trying for general rules that you hope will work everywhere from only a few experimental results.

If possible, extend the findings by checking with differently shaped magnets, perhaps with the poles not painted.

• ## 05 Hanging with magnetism!Mf02TAnugget05 Activity

### Suspension without contact

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

This is a simple demonstration which is guaranteed to capture the children's interest and can serve to really open up the idea of action without contact.

What to prepare

• clamp stand
• a very powerful permanent magnet
• iron object – the larger the better so long as the magnet will support it, or if the available magnets are more feeble, a paper clip

What happens during this activity

Clamp the magnet at the top of the stand. Tie the iron object to one end of the thread, secure the other end to the foot of the clamp stand and hold the object towards the magnet. If the gap between magnet and object is not too great, the object will hover in space!

Use this as a demonstration at the start of introducing magnets as objects that can act without contact, over a distance. It provides a highly engaging display of magnetic action at a distance at work.

As an extension you might also try slipping different materials in the gap between the magnet and the hanger to find out if the hanger can be shielded from the force of the magnet. The hanger falls away when a sheet of magnetic material is placed in the gap.

• ## 06 Magnet strength and action at a distanceMf02TAnugget06 Activity

### exploring variations in the force exerted

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

This is a simple exploration of the reduction of the magnetic force with distance.

What to prepare

• a bar magnet
• a paper clip
• several sheets of paper or card

What happens during this activity

Ask the children to use a magnet to pick up a paper clip. Then see how many pieces of paper or card can be inserted between the clip and the magnet before it no longer picks it up. You'll need to try this out beforehand with your magnets to see if paper or card is better.

This is an opportunity to develop investigative skills: designing, recording, and reporting.

As an extension ask the students to compare and contrast:

Teacher: Magnetism seems to work through the paper. How is this similar to gravity? How is it different to gravity?

• ## 07 Researching the Earth's magnetism Mf02TAnugget07 Activity

### Our home is a magnet…

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

The Earth's magnetism has a significant effect on what's possible for life on the planet. This interesting starting point can form the basis of a number of research activities.

What to prepare

• a compass
• an image of the Northern Lights ( Aurora Borealis)
• an image of a migratory bird

What happens during this activity

The Earth behaves as if it has a giant bar magnet inside.

You might launch the research by showing a floating needle being aligned by the Earth's magnetism. Here's how to set that up:

• magnetise the needle by rubbing the a pole of a bar magnet along it several times from the eye to the point
• use tape to stick the needle to the top of the cork
• fill a bowl with water
• float the needle on the cork in the water

The magnetised needle spins until it is aligned with the Earth's magnetism. You could emphasise that this is a magnetic effect by bringing a bar magnet alongside the bowl, and noticing the needle re-align.

The Earth's magnetism plays a really crucial role in protecting the Earth and is used in navigation. Pupils could research some interesting , for example: the Northern Lights; magnetic navigation in birds; early use of lodestone as a compass on land and at sea.

Teacher Tip: Scientists have been studying the Earth's magnetism for years and yet there is still no consensus on how it works. So don't be drawn into trying to explain it.

• ## 08 Finding northMf02TAnugget08 Activity

### A north-seeking compass

This a part of a suggested sequence:

A repertoire to develop ideas about magnets

What the activity is for

To introduce the idea of finding the magnetic north pole from anywhere on the Earth.

What to prepare

• a strong bar magnet, suspended in a sling, so that it is free to pivot
• a walker's compass

What happens during this activity

Hang the magnet in a sling, taking care not to have any magnetic materials nearby that it might be attracted to. Point to the XxxxVille (pick a town just north of you) seeking pole. Mark it.

Ask what would happen if you went further north up this island. You'd still be pointing to a XxxxVille-seeking pole! You can use this continuing tendency to point to things north of you to introduce the idea of north-seeking pole. This is usually contracted to the north pole of the magnet – really meaning the north-seeking pole.

Show the walker's compass, asking how you know where north is using such a compass.

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