A small world in a bottle
A miniature ecosystem is a small, safe model of a real one. Two clear bottles can make one. A grown-up cuts the bottles and tapes the sharp edges. Put soil and a few dead leaves at the bottom, then plant a few small seedlings, such as cress or grass. Water them lightly and close the bottles. We use no live animals. The seedlings are the producers: they make food from sunlight. The dead leaves and soil hold decomposers, so tiny living things break down the leaves and return minerals to the soil. The Sun is where the energy comes from. In the diagrams we draw an arrow from the Sun to the plants, and an arrow from the plants to the decomposers when the leaves die. Put the bottles in a bright place and look at them for two weeks.
| Part | Its job |
|---|---|
| seedlings | producers: make food using sunlight |
| soil | holds water and minerals, and the roots |
| dead leaves | food for decomposers |
| decomposers | break down dead leaves |
Make it (a grown-up helps). A grown-up cuts two clear bottles and tapes the edges. Fill one with soil, dead leaves and three seedlings. Close it and put it by a window. Draw it on day 1, day 7 and day 14. Write what changed. Draw two energy diagrams: one for the Sun and the plants, and one for the plants and the decomposers.