What a magnet actually does
Ask your child what a magnet does and you will probably hear "it sticks to metal." Only half right. DK's 1000 Words STEM notes that forces are among the new school words for things we cannot see2. Tonight you make one visible.
The key idea, from Aaron Isabelle and Gilbert Zinn's curriculum STEPS to STEM1:
it acts only on certain “magnetic” materials, such as iron.1
University of Illinois physicists name iron and many iron alloys as the most common magnetic materials, with nickel and cobalt as other fairly common magnetic metals3. Steel is iron with a small amount of carbon added7, which is why steel things stick. Copper counts as "non-magnetic": a magnet's pull on it is so weak you would need careful measuring to notice it3. Aluminum, the metal in soda cans, does not stick either4.
An object that pulls on iron, and on things made from iron, like steel17.
Say it: “Can you feel the pull before it touches?”Pull toward. Opposite poles attract1.
Say it: “Which things did the magnet pull toward it?”One of the two ends of a magnet, called north and south1.
Say it: “Where do you think the pull is strongest?”What you think will happen, said before you test it2.
Say it: “Sticks or not? Say it before we try.”Experiment 1: the sticks-or-not sorting test
It starts with a prediction and ends with a surprise. DK labels the parts of an experiment with kid words: question, prediction, method, results, conclusion2. Use them out loud.
- Fridge magnet with no cracks or loose pieces
- Paper clips counted out, and counted back in
- No tiny or high-powered magnets, no batteries
The sticks-or-not sorting test
- 1 fridge magnet
- Paper clip, foil ball, key, coin, spoon, pencil, rubber band, plastic lid
- A clean empty soup can and soda can (check rims for sharp edges)
- Two plates labeled "sticks" and "does not"
- Adult supervision: clips and coins are small parts.
- Your child predicts for each item: sticks or not? Write it in the chart.
- Touch the magnet to it and sort it onto a plate.
- Ask: what do the "sticks" things have in common? Hint for you: look for iron or steel17.
- Hold up both cans. Both are metal. Predict, then test: do they both stick? Soda cans are aluminum, which does not4. If the soup can sticks, ask what it might be made of.
| Item | Made of | Prediction | Result | Surprised? |
|---|---|---|---|---|
| EXAMPLE: paper clip | Steel wire | Sticks | Sticks | No |
| ____ | ____ | ____ | ____ | ____ |
| ____ | ____ | ____ | ____ | ____ |
| ____ | ____ | ____ | ____ | ____ |
- "Magnets stick to metal."
- "No, that one is wrong."
- "Magnets stick to some things. Which?"
- "What did you expect, and what happened?"
Poles: why magnets pull and push
Every magnet has two poles, north and south. In STEPS to STEM, students magnetize a steel blade and count clips at four points along it: the ends hold clips, the middle holds none1. Then the rule:
Remember that like poles repel, and unlike poles attract.1
-
01Label the ends.
Tape on each end of one magnet: A and B.
-
02Bring A close.
Move end A toward the second magnet. Pull or push? Flip it and repeat.
- 03
Experiment 2: paper clips through a stack of paper
A real fair test: change one thing (sheets), measure one thing (clips lifted), keep the rest the same.
The paper stack test
- The same fridge magnet
- 20 or more paper clips
- 8 squares of printer paper, a bit bigger than the magnet
- Pencil and the chart below
- Adult supervision: clips are small parts.
- Predict: how many clips through 0 sheets? Through 8?
- Spread the clips flat. Lay 1 sheet on top.
- Press the magnet on the paper, pinch both, lift, count the clips hanging under.
- Do 3 tries for 0, 1, 2, 4 and 8 sheets. Same magnet, same pinch.
| Sheets | Try 1 | Try 2 | Try 3 | Middle number |
|---|---|---|---|---|
| EXAMPLE: 2 sheets | 5 | 4 | 6 | 5 |
| 0 | ____ | ____ | ____ | ____ |
| 1 | ____ | ____ | ____ | ____ |
| 2 | ____ | ____ | ____ | ____ |
| 4 | ____ | ____ | ____ | ____ |
| 8 | ____ | ____ | ____ | ____ |
Middle number: sort the 3 tries and take the middle one (4, 5, 6 gives 5).
If the count drops as the stack grows, here is why. Illinois physicists say most materials don't do much to magnetic fields, which just go right through them5. The paper is not blocking anything. It adds distance, and the size of a magnetic force depends on the distance between the objects1.
The paper is not a wall. It is distance.
All metals stick to magnets.
Experiment 3: make your own magnet
The book magnetized its blade in a battery-powered coil1. Skip batteries: a magnet alone can do it.
Stroke a paper clip into a magnet
- The fridge magnet
- 1 large steel paper clip, straightened by an adult
- Small paper clips
- Adult supervision: the straightened clip has a pointy end.
- Test first: does the straight clip pick up a small clip?
- Stroke it end to end with one end of the magnet, then lift away. Same direction, same magnet end, every time6.
- After 10 strokes, count the clips it lifts. Do 10 more and count again, the strokes-versus-strength test Illinois physicists suggest6.
- Test again tomorrow. Does it still work?
Bonus question: hang a clip on the magnet, then try to hang a second clip on the first. Does it hold? Is the first clip acting like a magnet now? Pull the top clip off the magnet and watch the chain. How long a chain can your child build?
What to expect by age
Can: Sort sticks and does-not-stick, predict before testing, and use words like attract, push and pull12.
Try: Count clips with fingers and draw tallies. Skip the middle-number math.
Can: Run 3 tries per stack, find the middle number and explain the result with distance1.
Try: Bar graph per stack size, then a new test with fabric or cardboard.
If you want a kit for this
A fridge magnet and paper clips cover everything above. If you want a set that keeps the push-and-pull talk going, our Magnetic Travel Tiles connect with magnets and come with cars.
Build it with / Ages 5-7Magnetic Travel Tiles with CarsFlat shapes that stand up into roads and garages.$41.99GoP Toys sells the kit mentioned above. None of the sources cited tested our products.