A roof for every climate
People choose roof materials to suit the climate. In hot, dry places a flat roof of concrete or mud brick keeps the rooms cool, and families can use it for drying clothes. Where it rains a lot, a sloping roof of tiles lets the water run off. Each material has properties, such as colour, texture, hardness and how it reacts to water, that make it good for the job. A grown-up gives you kitchen powders to describe: sugar, salt, flour, baking soda and cornflour. Look at the colour. Feel with a finger: is it rough, smooth, soft, or gritty? Look at how it settles in a little water. You never taste or sniff a powder, because that is not safe and it is not needed for good evidence.
| Place | Roof | Why |
|---|---|---|
| hot and dry | flat, concrete or mud brick | keeps rooms cool |
| rainy | sloping, tiles | water runs off |
| Powder | Colour | Texture | In water |
|---|---|---|---|
| flour | white | soft, smooth | goes cloudy |
| salt | white | small hard grains | clear water |
Powder detectives (a grown-up gives you the powders). On a tray put a pinch of each powder in separate paper cups: sugar, salt, flour, baking soda, cornflour. Describe the colour and texture of each, and stir a little into water in a clear glass. Record your results in a table. Never taste or sniff. Wash your hands afterwards.