1. WATER.

2. Introduction 1ºWhat is water? 2ºThe water cycle 3ºWater and living things

3. What is water? Water is the most abundant substance on Earth and is the only one found in the atmosphere in liquid, solid and gaseous states.

4. The water cycle Water enters the atmosphere when the sun's heat evaporates. Hot air with dissolved water vapor rises and cools due to the lower density of the atmosphere. Upon cooling, it condenses and causes water droplets remain suspended in the air. These drops are grouped into clouds.

6. Water and living things Water is essential for life, because no organism survives without it. It is an essential constituent of living matter and hydrogen source for organisms. Living things are composed largely of water. Water is involved in all vital functions of plants and animals.