Plant Power - Spying on roots

Although plants usually stay in the one spot, their roots travel through the soil in many different directions searching for water. Think about the network of roots under the ground hugging the soil and protecting it from being washed or blown away.

In this activity you will be able to observe the roots of the plants through a special spy hole.

Materials

»	milk carton (1 litre size)
»	sharp knife or scissors
»	firm, clear plastic eg overhead projector transparency film or laminating off-cuts
»	small pot plant or seedling (beans, peas or lettuce are quick growing)
»	potting mix

What to do

1.	Cut the top off the milk carton and make some drainage holes in the bottom.
2.	Draw a spy hole on the side of the carton about 5cm x 5cm.
3.	Cut along the lines marked in the diagram so that you make a flap that can be opened and closed.
4.	Line the inside of the carton by inserting the transparency sheet so that the hole is covered.
5.	Fill the carton with potting mix and pot up the small plant in your new container.
6.	Over the next few weeks use your special spy hole to observe what is happening in the soil. Keep a record of your observations; you may like to draw a series of sketches to show the root development.

When you have finished with the experiment remove the plant by peeling away the carton. What shape does the soil have? What conclusions can you draw about the effect of roots on soil?