These creatures breathe through their skin. Lots of people don't like them but they play an important role in agriculture.
Aristotle called these creatures the intestines of the soil. We are, of course, talking about earthworms. Classes can set up a worm house and learn a lot about its inhabitants.
Take a plastic bottle and remove the top and the bottom to make a tube.
Place the tube in a terracotta plant pot, or similar, and fill the tube with soil. Build up thick layers of soil, and thinner layers of sand (or different-coloured soil) until the bottle is three-quarters full.
As you build up the layers, sprinkle with water to ensure that the soil is moist, but not wet. Place a layer of worm food on top of the soil - this could be leaves that have been broken into small pieces, or grass cuttings.
Now add a few worms. Earthworms can be found quite easily, especially when it is raining, or at night. You need to ensure that you do not overpopulate your worm house - a two-litre bottle would provide room for about eight worms.
Mark the different layers of soil on the tube using a marker pen. Place your earthworms into the container and wrap it in black paper. Place a piece of card over the top, with air holes in it. Place the worm house in a cool place. Make sure you keep checking that the soil does not dry out, and that the food does not run out.
After a couple of days, remove the black paper. You should observe that the worms have been active, eating the food, making burrows and mixing up the soil and sand. You may also observe their droppings - known as castings - which they deposit on the surface of the soil. These droppings are high in nutrients.
When you have finished with your wormery, talk to your class about appropriate places to release your worms, and let them go.
Sophie Duncan is project manager for science at the BBC www.bbc.co.uksn