Lesson
1 Work in pairs. Look at the diagram. Read the questions and take turns to ask and answer them.Write the answers below.Then write another question and answer it. 107
How to build a water filter
1 What can you see in the picture?
dirty water
peebles and rocks
2 What does a water filter do?
bottle top
3 How does it work?
coarse sand
fine sand
4 What is coarse and fine sand?
coffee filter
5
bottle lid bottle bottom
clean water
2 Work in pairs.Say how you think the water filter is made.Then read the steps and put them in the right order. 107
1
Cut a big plastic bottle in half. Fill the next quarter of the bottle with coarser sand.
Put a coffee filter over the opening of the bottle and replace the lid. Fill the bottom quarter of the top part of the bottle with fine sand. Make a small hole in the lid. Add small rocks to the third quarter of the bottle. Put the top half of the bottle upside down in the bottle half. You can now add dirty water to the bottom and wait for clean water to come out at the bottom.
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3 Work in groups. Rewrite the steps in Activity 2 using linkers such as: first , then , next , after that , or finally , where appropriate.
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