The water cycle is the natural process by which all the water on the earth's surface cycles through different states in the air and then returns to the earth's surface. Water in the earth's oceans, lakes and rivers is heated by the sun and changes into water vapour in the air. It then condenses into clouds and eventually falls back to earth in the form of rain, sleet, hail or snow. Using a water cycle model, students can learn about a variety of science concepts including evaporation, condensation, precipitation and states of matter. One hands-on approach to teaching the water cycle is to have students make their own water cycle models.
Set the empty yoghurt cup into the large glass bowl.
Fill the glass bowl with a little water being careful not to get any liquid in the yoghurt container.
Cover the bowl with a piece of cling film. Pull it taut, and place the rubber band around the rim of the bowl to hold the cling film in place.
Place the small weight on top of the cling film in the centre of the bowl.
Put the bowl in a sunny windowsill or directly underneath a lamp.
Observe the water cycle model and record what happens to the water inside the bowl. Discuss what students record.
When heated by the sun or lamp, the water in the glass bowl should condense on the cling film. It will then fall from the cling film into the empty yoghurt cup.
An adult should position and handle the lamp if that is the heat source used.