3
Water and light
Workbook 2: Topic 3.2, pp. 32–34
GoalSay whether a material is waterproof, absorbent or transparent.
New words
waterproof · does not let water throughabsorbent · soaks up watertransparent · you can see clearly through itopaque · you cannot see through it
Explanation
Some properties tell us what happens with water and light. A waterproof material does not let water through. Plastic and rubber are waterproof, so they are good for boots. An absorbent material soaks water up, like a sponge or a towel. Transparent materials let light through, so you can see through them. An opaque material does not let light through, so you cannot see through it, like a wooden door.
Worked examples
Leo wears rain boots to jump in puddles. The boots are waterproof, so his feet stay dry.
After washing, Omar dries his hands on a cotton towel. The towel soaks up the water. It is absorbent.
We can see the garden through the window glass. It is transparent. We cannot see through a wooden door. It is opaque.
Class activity
Sort by seeing (with an adult): look at a window, a cup, a plastic bag and a book. Hold each one up and look through it. Sort them into “see through” and “cannot see through”. Then compare a kitchen towel and a plastic bag: which would soak up spilled water?
Practice
1
Which material is absorbent: a sponge or a plastic bag?
The sponge.
2
Why do we make raincoats from waterproof material?
Because water does not go through it, so we stay dry.
3
Is a book transparent or opaque?
Opaque. You cannot see through it.
4
Which word means ‘soaks up water’?
Absorbent.