1. WATER CYCLE What percent of our planet is covered by water? 70 % Of that 70 %, how much of that water is in the oceans? 97 %

2. Evaporation: Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.

3. Evaporation occurs because water gains thermal energy.

4. The main source of energy is the sun. The sun drives the water cycle.

5. Do plants sweat? Well, sort of.... people perspire (sweat) and plants transpire. Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air.

6. Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation. Condensation : Are clouds a gas or liquid? Clouds are drops of liquid!

7. You can see the same sort of thing at home... pour a glass of cold water on a hot day and watch what happens. Water forms on the outside of the glass. Is thermal energy gained or lost with condensation? LOST!!

8. Precipitation: Precipitation occurs when the clouds get too heavy to hold all the moisture. Water falls back to the earth in the form of rain, hail, sleet or snow.

9. When water falls to the Earth, the water seeps into the soil because of the force of gravity. This seeping is called infiltration.

10. This water will eventually seep through layers of the Earth's surface where impurities filter out.

11. Or the water flows over the land and into bodies of water, such as rivers and lakes. When water collects instead of soaking into the ground, we say it accumulates.

12. If the water does not infiltrate, then it runs over the ground to lower elevations. We call this run-off.

13. Sometimes this water collects nutrients from the soil it runs over, making the valley good for plant growth.

14. When a water-bearing rock readily transmits water to wells and springs, it is called an aquifer. Wells can be drilled into the aquifers and water can be pumped out. If it flows out on its own, we call these artesian wells.

17. Water cycle in action: http://www.bbc.co.uk/schools/riversandcoasts/water_cycle/rivers/pg_02_flash.shtml

18. http://marg.mhost.com/Grade3/Watercycle.htm Check for understanding!!