Earth's water cycles through the atmosphere in several stages. First is evaporation, when the heat from the sun turns water into vapour. When the vapour gets cold, it turns back into liquid and forms clouds in the next stage, condensation. Precipitation, the third stage, occurs when clouds release their water as rain, hail, sleet or snow. Finally, collection is when water soaks into the ground and is used by plant life. The same holds true for the vegetation in a rainforest in a jar, an educational project that you can create with a few basic supplies.
Line the bottom of the glass jar with one to two inches of pea gravel or sand. Spread the gravel or sand to create an even layer.
Place a one- to two-inch layer of potting soil and compost over the gravel or sand. Make sure that the top of the compost and soil fills no more than one-fourth of the height of the jar.
Plant houseplants, which can include African violets or ferns, in the soil. Use your finger to make several small wells in the soil, then put one plant in each well. Pat the soil around each plant to make sure it is stable.
Water the plants well with a spray bottle, then put the lid on the jar. If there is no lid, use cling wrap or a piece of glass as a cover.
Place the jar in an area in your home or classroom that receives indirect sunlight. The plants are now ready to begin the water cycle and to become a miniature rainforest. Observe water droplets condensing on the lid and sides of the jar and then falling onto the plants.
Check the rainforest every few weeks to ensure that the plants have plenty of water.
If you see excess moisture or mould inside the jar, remove the lid for a while to allow the rainforest to dry slightly.