A sequence to develop ideas about magnets
Classroom Activity for 5-11
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;
pullseeing 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
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.
The ideas are developed in the Physics Narrative.
Here children explore action at a distance
You can use this activity to introduce the idea of a magnetic pole, and see how to magnetic poles interact.
This demonstration is useful for introducing the idea of 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.
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.
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.
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.
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.
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.
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 idea of a magnetic pole is seemingly simple, but can lead to complications if not dealt with carefully.
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.
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
Find out more from the Physics Narrative.