Teacher cards / Activity 06
For teachers and helpers. Adult supervised. Not for student screens.Make a Compass
How can a tiny needle find north?
★The card
Put this card on the board for the class, or print it. Save the card
1Before class
The day before
- Make one compass yourself first. It takes five minutes and shows you whether your needles work.
- Use steel sewing needles. Some needles are weak. Test each kind before class and use the one that turns best.
- Cut the corks into slices about one centimeter thick at home with a sharp knife on a cutting board. Do not cut in class.
- Find north with a real compass. Stick a strip of tape on the wall and write N on it. Do this far from the magnets.
- Count the needles into a closed box. Count them again after each group and at the end.
- Decide who handles needles. Only the K to 5 teacher do it. Helpers and children never touch a needle.
- Ask if anyone wears a medical device or a hearing device. Keep magnets well away from them.
- Give your helpers the helper guide on this page.
Ten minutes before kids arrive
- Choose wood or plastic tables. Steel tables and nearby metal can pull the needle off north.
- Put one clear plastic bowl on each table. Fill it about two thirds with room temperature water. Do not use glass.
- Set a cork slice on a paper towel beside each bowl.
- Keep the needles in one closed box and the bar magnets in another. Both stay on the adult table.
- Put all phones, Chromebooks, watches and bank cards in a bag across the room, at least two meters from the magnets.
- Switch off fans. Moving air spins the cork.
- Put a towel and a trash bag where helpers can reach them.
- Put this card up on the board.
Safety and care
- An adult stays with every group for the whole activity. The K to 5 teacher is the responsible adult in the room.
- Only the K to 5 teacher touches a needle. Helpers and children do not hold, pass or float one with a needle in it.
- A blunt needle is not an option because it will not go through the cork. So the sharp needle stays in the adult's hands from the box to the cork and back to the box.
- The needle ends stick out of the cork. Children sit with their hands in their laps and look. They never touch the cork.
- Store needles in a closed box. Count them out before class, after each group and at the end. A missing needle means stop and look.
- Keep magnets away from phones, Chromebooks, watches, bank cards and hearing devices.
- Nothing goes in mouths. The water is not for drinking.
- Spilled water makes a slip hazard. Wipe the floor at once.
- Wash hands after.
2Materials for 15 students
| Item | Per group | Whole class | Notes |
|---|---|---|---|
| Steel sewing needle | 1 | 5 | Kept in the adult's hands and the closed box. Count in and out. |
| Bar magnet | 1 | 5 | Kept by the adult. Goes back in its box after stroking. |
| Cork slice, about 1 centimeter thick | 1 | 5 | Cut at home by an adult. Bring two spares for the class. |
| Clear plastic bowl | 1 | 5 | Wide enough for the cork to float without touching the sides. |
| Water, room temperature | 3 cups | 15 cups | About two thirds of a bowl. |
| Towels | 2 | 10 | For spills. |
| Pencils | 3 | 15 | |
| Plain paper, folded in half | 3 | 15 | Each child draws and records. |
| Real hand compass | 1 | Only used to mark north on the wall. Keep it away from magnets. | |
| Masking tape | 1 roll | For the N on the wall. | |
| Closed box for needles | 1 | A lidded box that stays shut between turns. | |
| Closed box for magnets | 1 | Keeps magnets away from the bowls. | |
| Bag for phones and Chromebooks | 1 | Stored across the room. | |
| Trash bag | 1 | For paper towels. |
How to set up the room
- Put the five bowl tables in a wide ring with at least two meters between them.
- Put the N on the wall where every group can see it.
- Keep the adult table with the needle box and the magnet box at the side of the room.
- Keep walking space clear and floors dry.
3Run it in 30 minutes
Groups sit at their bowls. Show the board. Ask for a guess. Can a plain needle find north?
The K to 5 teacher visits each group in turn. The adult strokes the needle 30 times while the children count out loud. Then the adult pushes the needle through the cork. Groups that wait draw their bowl and their guess.
The adult floats the cork in the middle of the bowl. Everyone sits quiet and watches. When the needle settles, compare it with the N on the wall. A helper turns the bowl by its outside edge. Watch the needle swing back.
Bring the class together. Which way did every needle point? Why?
The adult takes out the needles and counts them. Magnets go back in the box. Empty the bowls. Dry the tables.
4What the kids do
- The adult strokes the needle 30 times with one end of the magnet. It always goes the same way. Count out loud together.
- The magnet goes back in its box. It must stay away from the bowl.
- The adult pushes the needle through the cork slice from one side to the other.
- The adult floats the cork in the middle of the bowl. Hands stay in laps.
- Wait and watch. The needle turns and slowly settles.
- Look at the N on the wall. Which way is the red end of the needle pointing?
- Your helper turns the bowl by its outside. What does the needle do?
Match it to the grade
Watch the needle turn and say it finds north. Find the N on the wall. Draw the bowl and the needle.
Say which way the needle points when it stops. Turn the bowl and see if it points the same way. Draw it.
Use the needle to tell which wall of the room is north, south, east and west. Explain how Earth acts like a magnet. Say what could spoil the test.
5Helper guide for older students
Your job
- Lead one group of three. Practice the setup the day before.
- Help the children count the strokes out loud.
- Turn the bowl by its outside edge when the adult says so.
- Ask questions and let the children guess before you explain.
- Keep phones and Chromebooks far from the magnets.
Say things like this
- Which way do you think the needle will point?
- Watch it slowly. What is it doing?
- Let us turn the bowl and see.
- That is a good guess. How could we test it?
Please do not
- Do not touch a needle. Not even the one in the cork.
- Do not move the magnet near the bowl.
- Do not let anyone lean over the bowl.
- Do not bump the table. It will send the needle spinning.
- Do not say a guess is wrong. Say let us test it.
6Talk it over
Questions to ask
- What did the needle do when it was floated?
- Which way did the needle point when it stopped? How do you know?
- What happened when the bowl was turned?
- What do you think the magnet did to the needle?
- What could throw a compass off?
- Grades 4 and 5. Why does the needle need to float to work well?
The science, in plain words
Earth acts like a giant bar magnet. Its magnetic field runs through the room. A steel needle holds many tiny magnetic regions that point every which way, so it is not magnetic at first. Stroking it with a magnet in one direction lines many of them up. The needle becomes a weak magnet. Floating it on cork lets it turn with very little friction. The needle then lines up with Earth's magnetic field and one end points toward Earth's magnetic north. That is close to true north but not exactly the same. The effect is weak. Steel furniture, magnets, electronics and moving air can all spoil the test. A magnetized needle can also lose strength if it is dropped or hit.
Where you see it
- Hikers and sailors use compasses to find their way.
- Scientists think some birds and sea turtles sense Earth's magnetic field to travel long distances.
- A phone has a tiny magnetic sensor inside that works like a compass.
7If it goes wrong
| What you see | What to do |
|---|---|
| The needle does not turn | Stroke it more times. Always go the same direction and lift the magnet away between strokes. Try a different needle. |
| The cork spins around and around | Switch off fans. Keep everyone still and wait for the water to settle. |
| The needle points a different way each time | Move the bowl away from steel tables, shelves and electronics. Check that every magnet is back in its box. |
| The cork sinks | Use a fresh dry slice. Make it a little thicker. |
| The cork sticks to the side of the bowl | The adult floats it back to the middle. Use a wider bowl. |
| The needle slides out of the cork | The adult pushes it through a little farther so it fits firmly. |
Clean up
- The adult pulls each needle out of its cork and puts it in the closed box
- Count the needles back in. There should be 5
- Count the magnets back in their box
- Pour out the water and dry the bowls and tables
- Let the corks dry on a paper towel
- Wash hands
Go further
- The adult slowly brings a magnet near the bowl. Watch the needle follow it.
- Make a second needle with only 10 strokes. Which one is stronger?
- Draw a map of the room and mark north.
- Go outside with a real compass and find north. Does it agree with the needle?
Built by Science Fenns for teachers and student helpers. Keep supervising every group the whole time.