Sorting living things into groups

Biology · Key Stage 1 · The School

Grouping by what you see

You can sort animals by asking simple questions. Does it have legs? How many? Does it have fur, feathers or scales? Does it fly? Does it live in water? Each question splits the animals into two piles, and asking a few in a row gets you to quite a small group.

The main groups

MAMMALS have fur or hair and feed their babies milk — dogs, cats, mice, whales and people. BIRDS have feathers, wings and a beak. FISH have scales and gills and live in water. REPTILES have dry scaly skin. AMPHIBIANS like frogs live partly in water and partly on land. INSECTS have six legs.

Why sort at all

Sorting is not just tidying. Once you know an animal is a mammal, you already know several things about it without being told — it has fur or hair, it feeds its young milk, it breathes air. Groups let you predict, and predicting is what makes science useful.

A SHARK: gills, scales, cold-blooded, lays eggs — a fish. A DOLPHIN: comes up to breathe air, warm-blooded, feeds its young milk — a mammal, despite living in the sea and being that shape. A PENGUIN: feathers, beak, lays eggs — a bird, despite not flying. All three swim, so swimming tells you nothing. Sort by what an animal HAS, not by where it lives.

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