An eco-column is a deceptively simple way to demonstrate ecosystems and food chains in the classroom.

This cheap and simple ecosystems practical uses 2 litre soft drinks bottles as a basis.

A pond can be established in the bottom. Add some mud, sand and gravel, pond water and a few pieces of pond weed  (see our separate 'Portable Pond' resource). An insect eating bog can be established above this. Venus fly traps, sundews and butterworts will grow well in these units. A 'fly ranch' can be maintained on rotting garden compost, which will contain the eggs and larvae of small insects e.g. fruit flies. These will hatch out in the eco-column, and feed both the spiders and the insect eating plants. A spider's den can be established in the top of the column.

Students can identify and record the species within their eco-column, draw the food chains, and then predict how the populations of the different species will change. Students can then record the changes at regular intervals, and discuss the implications.

All animals which you may be studying in the eco-column (insects, spiders, tadpoles and other pond creatures) are living things so should be treated with care and released back to their natural habitat at the end of the study.