1. WALT: how to clean water.

2. How can we clean water? While I was trekking in Nepal I had to find a method to obtain pure water. Imagine you are on an expedition. How are you going to clean the muddy water so that it is drinkable?

3. Write a step-by-step method Describe exactly what you would do. Which pieces of apparatus do you need. Think about safety issues.

4. Class method

5. 1.Seive water to remove large stones. 2.Filter water to remove dirt and small particles.

6. Do we now have pure water?

7. After filtering the water looks clear. It is not pure because there are substances dissolved in the water. http://www.youtube.com/watch?v=gN9euz9jzwc

8. How can we check if water has solids dissolved in it?

9. Complete your method of purification 1.Seive water to remove large stones. 2.Filter water to remove dirt and small particles. 3.Evaporate off the pure water.

10. Quick Quiz 1.What is the name for the process used to separate things that have not dissolved in a liquid? 2. Name a solid that dissolves in water? 3.Name a solid that does not dissolve in water? 4.How could you prove that sea water had salt in it?