Classification of Animals

A whale isn't a fish and a bat isn't a bird — and here's how to never get fooled again. Every year, the trickiest animal questions in the PSLE Science paper catch students out because they guess from where the animal lives or whether it can fly. But scientists don't sort animals that way. They look at three clues: what covers the body, how the animal breathes, and how its young are born. Once you learn those three clues, you can place almost any animal into its group — even the sneaky ones.

Parents: the blue dotted words are tappable definitions, and the sorting game below lets your child predict first, then check. Let them tap through it and explain their guess out loud — saying the keyword is how it sticks.

By the end you'll be able to put any animal into its group using its body covering, how it breathes, and how its young are born. The six groups we'll master are: mammals, birds, fish, amphibians, reptiles, and insects. Let's go.

Mammals

A mammal's body is covered with hair or fur. Mammals breathe air with their lungs. Most mammals give birth to live young (the baby is not hatched from an egg), and every mammal mother feeds her young with milk from her own body.

Here's the trick: a mammal does not have to live on land. A whale and a dolphin live in the sea, but they swim up to breathe air with lungs and they feed their young milk — so they are mammals, not fish. A bat can fly, but it has hair and feeds its young milk — so it is a mammal, not a bird. The keyword is mammal.

Birds

A bird's body is covered with feathers. Birds breathe with lungs, have a beak and a pair of wings, and they lay eggs.

Watch out: not every bird can fly. A penguin, an ostrich, an emu and a kiwi all have feathers and lay eggs, so they are birds — even though they cannot fly. Don't let flying fool you. The keyword is bird.

Fish

A fish's body is usually covered with scales. A fish breathes underwater using gills, has fins to swim, and lays eggs. Fish live in water their whole lives. The keyword is fish.

Amphibians

An amphibian has thin, moist skin. When it is young (like a tadpole), it lives in water and breathes with gills. When it grows into an adult (like a frog), it breathes with lungs and through its moist skin, and can live on land. Amphibians lay eggs, usually in water. Frogs, toads and salamanders are amphibians. The keyword is amphibian.

Reptiles

A reptile's body is covered with dry, scaly skin. Reptiles breathe with lungs and lay eggs with leathery shells, usually on land. Snakes, lizards, turtles and crocodiles are reptiles. The keyword is reptile.

Insects

An insect's body has 3 parts — head, thorax and abdomen — and 6 legs. Many insects have a hard outer covering called an exoskeleton, and they breathe through tiny holes in the body. Insects lay eggs. Ants, bees and butterflies are insects. The keyword is insect.

Don't get tricked

Most wrong answers come from one mistake: deciding the group by where the animal lives or whether it flies. A whale lives in the sea but is a mammal. A bat flies but is a mammal. A penguin cannot fly but is still a bird. A platypus and a spiny anteater are mammals even though they lay eggs — because they have hair and feed their young milk. Always go back to the three clues: body covering, how it breathes, and how its young are born.

Try the sorting game. Predict first, then tap each animal to check its group.

🔬

Sort the animal into its group

🤔 Predict first: Is a bat a mammal or a bird?

MammalBird

Use the identification key below to work out each animal's group step by step — the same way a real scientist would.

🔬

Use a classification key

🤔 Predict first: A bat flies and has wings. Bird or mammal?

BirdMammal

Now the most famous trap of all. Predict before you reveal.

Quick recap

🎯 Mastery check

Answer all 8 — your progress is saved on this device.

1. A whale lives in the sea its whole life. Which group does it belong to, and why?

   Fish, because it lives in waterMammal, because it breathes with lungs and feeds its young milkAmphibian, because it can swim

2. A bat can fly through the night sky. Which group is it in?

   Bird, because it can flyInsect, because it has wingsMammal, because it has hair and feeds its young milk

3. A penguin cannot fly at all. What group does it belong to?

   MammalBirdFish

4. A platypus lays eggs but has hair and feeds its young milk. Which group is it in?

   Reptile, because it lays eggsBird, because it lays eggsMammal, because it has hair and feeds its young milk

5. A goldfish breathes underwater. Which body part does it use to breathe?

   LungsGillsMoist skin

6. A frog has moist skin and starts life as a tadpole in water. Which group is it in?

   ReptileAmphibianFish

7. A turtle has dry, scaly skin and lays leathery eggs on land. Which group is it in?

   AmphibianFishReptile

8. A butterfly has a body with 3 parts and 6 legs. Which group does it belong to?

   Bird, because it has wingsInsect, because it has 3 body parts and 6 legsReptile, because it lays eggs

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