Grade 3 (age 8-9)

grade 3 Animal Life Cycles

Animals are born as eggs or babies, grow up, and then lay eggs or have young of their own, carrying on their life cycle. A butterfly goes from egg to caterpillar to pupa to adult, a frog from egg to tadpole to frog, and a chicken from egg to chick to adult hen. Among insects, a life cycle with a pupa stage, like the butterfly's, is complete metamorphosis; one without, like the grasshopper's, is incomplete metamorphosis. Choose an animal in the first picture to see its life cycle go around in a loop, and compare the two kinds of metamorphosis side by side in the second.

Animal life cycles

🦋 What is a life cycle?

①A life cycle is how an animal is born, grows and has young of its own

②Butterfly: egg → caterpillar → pupa → adult (complete metamorphosis)

③Frog: egg → tadpole → tadpole with hind legs → frog; the tadpole breathes with gills in water, then grows legs and loses its tail, becoming a frog that can also live on land

④Chicken: egg → chick → young chicken → adult; it grows bigger without changing much in shape

Two kinds of metamorphosis

💡 How the two kinds differ

①Complete metamorphosis has a pupa stage (butterflies, bees, ladybugs)

②In incomplete metamorphosis there is no pupa; the young (nymph) sheds its skin as it grows into an adult (grasshoppers, dragonflies, cicadas)

③Insects with complete metamorphosis change their bodies completely inside the pupa

④In complete metamorphosis each stage eats something different: a caterpillar eats leaves, but a butterfly drinks nectar from flowers

⑤Many animals, such as birds and mammals, do not go through metamorphosis

Summary

Complete metamorphosis

Egg → Larva → Pupa → Adult

Butterflies, ladybugs and bees go through a pupa stage

Incomplete metamorphosis

Egg → Nymph → Adult

Grasshoppers, dragonflies and cicadas grow without a pupa

🎯 Key points

①A life cycle is the whole process of being born, growing and having young

②Complete metamorphosis has a pupa stage

③Incomplete metamorphosis has no pupa

④A frog changes a lot from tadpole to frog, while a chicken grows without changing much in shape

⑤Food and living place can change from stage to stage

Examples and Unit Test

Example 1

Put egg, caterpillar, pupa and adult butterfly in the order of a butterfly's life cycle.

A butterfly goes through a pupa stage: complete metamorphosis.

So the order is egg → caterpillar → pupa → adult butterfly.

▸ Egg → caterpillar → pupa → adult butterfly

Choose the butterfly in the picture and the four stages go around in a loop; the eggs an adult lays start the cycle again.

Example 2

How do the life cycles of a butterfly and a grasshopper differ?

A butterfly goes through a pupa stage: complete metamorphosis.

A grasshopper has no pupa; the nymph sheds its skin and becomes an adult: incomplete metamorphosis.

▸ Butterfly: complete (with a pupa) / Grasshopper: incomplete (no pupa)

As the second picture shows, a pupa stage means complete metamorphosis, and no pupa means incomplete.

Unit-test style

Which statement about animal life cycles is correct?

①All insects go through a pupa stage

②A butterfly goes through complete metamorphosis with a pupa stage

③A grasshopper has a pupa stage

④A chicken goes through metamorphosis

⑤A life cycle starts when an animal becomes an adult

▸ ② A butterfly goes through complete metamorphosis with a pupa stage

A butterfly goes egg → caterpillar → pupa → adult: complete metamorphosis.

Some insects, like grasshoppers, have no pupa (①, ③); a chicken just grows from a chick without metamorphosis (④); and a life cycle starts at birth (⑤).

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Last updated 2026-10-17