These building bricks are made of plastic. Tom tries to pick them up with a magnet. But the magnet will not pick up the bricks. Why will the magnet not pick up the bricks?

Studying forces in science at school you will have used simple magnets. They are fun to use. You can pick up things made of iron and steel. At home, you may have fridge magnets - they use force to stick to the door of the fridge - as long as it contains some iron or steel. Magnets are very useful and simple to use.