Magnetic money

I often overhear  the children talking about their day at school. So I know that the last few weeks both of them have been enjoying their science lessons. D in Y4 has been learning about forces, while P in Y1 has been investigating the properties of materials. The common theme between the two topics is magnetism, so a couple of days ago I grabbed the opportunity and asked the children to help me with a “Magnetic Money” investigation.

This is what it is all about: Children investigate the magnetic properties of 1p and 2p coins. It is not as straightforward as it may sound, because as they are going to find out soon some coins can be magnetic, while others are not. This does not depend on the value. So they need to solve the mystery. When is a 2p coin magnetic?

For this activity you are going to need:

1p, 2p coins (make sure that you have a mixture of old and new coins)

Fridge magnet

Sheet of paper to record your findings

Hint: In 1992 the composition of 1p and 2p coins was changed from bronze to copper-plated steel. As a result coins produced after 1992 are magnetic. Older coins are not.

Here is a “transcript” of the discussion I had with my daughter.

Me: Are these coins magnetic? Let’s find out.

D tried a 2p coin. The coin was attracted by the magnet.

D: Oh this is magnetic.

Me: Do you think that all coins are magnetic?

D: Yes. My hypothesis is that all coins are magnetic!

So she tried another 2p coin and to her surprise this time it was not attracted by the magnet.

D: Oh this is so strange. This coin is not magnetic…

Me: Why do you think that this coin is not magnetic?

D: Because it does not stick to the magnet

Me: Why is that? Does it mean that the two coins are different?

D: They look the same to me.

She put one on top of the other. She points that the two coins have the same diameter.

Me: What about their thickness?

D: Oh, one of them is slightly thicker. Is this the magnetic one?

Me: What about the weight?

She balanced the two coins on the tip of her two middle fingers

D: They feel the same.

All this time P is playing with his magnet and coins and is shorting out magnetic and non-magnetic coins in two piles. He does not look interested in our investigation but he is obviously intrigued by the way the investigation is going. So he decides to intervene. In fact, they just had talked about magnetism the previous day at school, so he had something really useful insight to add to the discussion.

P: I know why! They are made from different materials.

D: Well done P! That could explain everything.

Me: What do you think you could do next?

D. I will try all other coins and sort them out.

So she tries all 1p and 2p coins and end ups with four piles of coins.

Me: How can we predict if a coin is magnetic or not?

D:That’s tricky, because we can not tell what material is made from just by looking at it.

She was really puzzled and could not come up with any ideas

Me: Look at the dates on the coin. What do you notice?

She records the dates of the coins in a table.

D: All the magnetic coins have dates after 2000. There is only one made in 1999. The non magnetic coins are really old.

She looks at one coin dated 1971.

D: Cool! This is  older than you.

Next I gave her a new pile of 1p and 2p coins.

Me: I want you to sort this out for me please. But there is a catch, you are now allowed to use a magnet this time. I want you to predict which coins are magnetic.

D: That’s easy-peasy mum. I only have to look at the year they were made.

She checked the dates and then uses the magnet to confirm her findings.

This is such a simple activity but D really enjoyed it so much that she plans to demonstrate it in her next science class.

Throughout this investigation D recorded her finding in a table with three columns

Value – Year – Magnetic?

When trying this at home encourage your child to use appropriate vocabulary such as Hypothesis Prediction, Investigation

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