Rocks and soil are natural materials — Science, 4–6 years
Rocks and soil come from the Earth, not from a factory. Rocks can be hard and solid, while soil is a mixture of small pieces, air, water and sometimes living things.
Earth materials are not all alike
A pebble, a handful of soil and a piece of clay all come from the Earth, but they do not feel or behave in the same way. A pebble is one hard piece, while soil may contain sand, tiny rock pieces, water, air and roots. Looking at what is inside helps us tell these materials apart.
Why examine soil and rocks?
People needed to know which ground was safe to walk on, which soil could help plants grow and which rocks could be used for building. A brown surface can hide very different materials underneath. Examining samples with our eyes, fingers and simple tools gives better answers than judging only by colour.
Look closely at soil
Put one spoonful of dry soil on white paper. Step 1: spot the dark and light pieces; step 2: gently separate a few bits and notice sand, tiny stones or roots; step 3: add a drop of water and see which parts become darker. The sample is not one solid material: it is a mixture.
Brown does not mean the same
It is reasonable to group all brown things together because colour is quick to notice. But brown soil, a brown rock and a piece of wood can feel, break and hold water differently. Colour can give a clue, yet it cannot tell us everything about what a natural material is like.
Ground under our feet
Soil supports plants in gardens, parks and fields, while rocks are used in paths, walls and buildings. People choose materials by testing what they are like, not just by picking the prettiest piece. Looking after soil also matters, because it can support roots and small living things.
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