The investigation could be refined in a variety of ways. If the children have identified that woodlice feed primarily on dead leaves, you could suggest that the leaves of some species might be more readily broken down by woodlice than others are. They prefer to eat leaves high in nutrients e.g. ash and sycamore. Leaves such as oak and beech have a lower nitrogen content but are rich in tannins and waxes, making them unpalatable and less favoured. Investigating the diet of earthworms Similar experiments to those described previously could be carried out with litter feeding earthworms.
Earthworms also form a very important decomposer link in many food chains.
They can be kept in the classroom in a wormery or even in plastic pots filled with soil. Different types of food can be placed on the surface of the soil and the worms will selectively pull down their preferred food into the soil. Be sure to collect earthworms for this exercise from the surface litter layer and not from deeper in the soil, where worms are more likely to be soil feeders. The favoured food of litter feeding earthworms is, of course, fallen leaves, though they show distinct preferences. Ash, elm and poplar are all favoured and for this reason persist on the ground only for a few weeks after falling.