Grouping living things by what they have in common
Aprende
To group is to put together the living things that look alike in some way. Before grouping, you choose what you are going to look at. This is called a criterion.
One criterion is counting the legs. Those with 4 legs go together. Those with 6 legs go in another group.
Animals, sorted by their legs Another criterion is what covers the body: hair, feathers, scales or smooth skin. The dog has hair and the pigeon has feathers.
What covers the body A good criterion can be checked: you count or you look. “The prettiest” does not work. Everyone thinks differently.
With another criterion you get other groups. If you look at where they live, the fish and the dolphin go together, in the water. The dolphin is not a fish: its mother gives it milk.
The same animals, sorted by where they live Groups can be inside other groups. Vertebrates have a backbone; invertebrates do not. Mammals are a group inside the vertebrates.
Groups inside groups With the living things you see every day you can make three groups: animals, plants and mushrooms.
Worked examples
Ejemplo 1
Gus writes down the minibeasts from the playground in his delivery book: a bee, an ant, a spider and a ladybird. He groups them by legs. How many go in the 6-legs group?
- The criterion is how many legs each minibeast has.
- The bee, the ant and the ladybird have 6 legs.
- The spider has 8 legs: it goes in another group.
Three minibeasts go in the 6-legs group.
¡Ojo! Many children put the spider in too, because it is a small minibeast with legs.
Ejemplo 2
Tony is riding his bike through the park. He sees a pigeon, a cat, a dog and a hen. He makes a group with the ones that have feathers. Which ones go in it?
- The criterion is what covers the body.
- The pigeon and the hen have feathers.
- The cat and the dog have hair: they go in another group.
The pigeon and the hen go in.
¡Ojo! Many children put them all together, because all four are in the same park.
Ejemplo 3
Ellie groups a fish, a dolphin and a cat by where they live. She puts the dolphin with the fish. Does that mean the dolphin is a fish?
- The criterion is where they live. The fish and the dolphin live in the water.
- That criterion does not tell which animal each one is.
- The dolphin is not a fish: its mother gives it milk.
They go together because of where they live, but the dolphin is not a fish.
¡Ojo! Many children think that everything that lives in the water is a fish.
Un reto para pensar
Choose five living things from your home or your neighbourhood. Do not touch or disturb any of them. Group them in two different ways and draw the groups. Say which criterion you used each time.
Practica
Rondas de 10 preguntas. Elige el nivel:
Next topic: Species and the scientific name of living things →