Life Around Us
Water — the essence of life
Name the forms water takes, follow it round the water cycle, tell groundwater from surface water, and recognise the plants and animals that live in freshwater.
Look at a globe and it is mostly blue. But the greater part of that blue is salty sea water, and what is left over — the freshwater in rivers, ponds, lakes and under the ground — is a very small share of it. Pour the whole of the Earth's water into one glass and the freshwater in it would come to about a teaspoonful. People, animals, birds and plants drink from that teaspoon, and crops are grown with it.
Water wears three faces
Rain is water in its liquid form. Ice and snow are water in its solid form. Steam is water in its vapour form. It is one substance throughout: water can turn into ice and into steam, and it can come back to liquid again.
The water cycle
The Sun's heat lifts water out of oceans and rivers as vapour. High up, the vapour makes clouds. The clouds come down again as rain, snow and hail, and the water finds its way back to rivers, lakes and oceans. This constant circular movement of water in nature is called the water cycle.
Two places the freshwater sits
Rain that soaks into the soil sinks through soil and rock and is stored deep underground; that store is groundwater, and wells, borewells, tube wells and handpumps are dug to reach it. Rain that stays on top fills rivers, ponds and lakes — surface water. A cemented road or a paved courtyard turns rain away from the ground, so open ground, soak pits, ponds and trees are what let it back in.
Have a play
A stretch of land that water has shaped, and the name of each part of it.
Tap any part of the picture.
Worked example
Crumple a sheet of newspaper, lay a second sheet over it, press the folds down into gentle slopes, and pour mustard seeds onto the highest point. What does that show about rivers?
Watch where the seeds go first. They run downhill from the high point, and they do not run in one straight line.
Nothing is pushing them sideways. The slope under them decides which way they take, and the slope is not the same in each direction.
Try it together
Work out what happens inside a sealed bag of coloured water left in the sunlight.
Draw a sun and clouds on a transparent bag, fill a third of it with coloured water, seal it and put it in the sun. Come back a few hours later.
1.The water in the bag warms up. What is supplying that heat?
Have a go
Have a go on your own. Put a drop of water on a leaf and it beads up instead of soaking in. Which one-word coating on the leaf's surface is keeping it out?
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.