Year 3 · Science · Biological sciences
Growing and changing
Children explore life cycles, such as a frog growing from egg to tadpole to adult and a joey growing in its mother's pouch, and compare young with their parents.
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These lessons were written around Australian Curriculum strands and matched to UK year groups by age (Year 1 is the year a child turns 6 in England). They are not mapped to the National Curriculum in England or the curricula of Scotland, Wales or Northern Ireland, so check them against your own plans.
Learning goals
Learners will
- Describe a life cycle as the stages a living thing goes through as it grows.
- Put the stages of a frog's life cycle in order and describe how a marsupial joey grows in a pouch.
- Compare young animals with their parents.
Success looks like
- I can explain what a life cycle is.
- I can order egg, tadpole, froglet and adult frog.
- I can say how a young animal is the same as and different from its parent.
The big idea
All living things grow and change. The stages a living thing goes through, from the start of its life to being an adult that has young of its own, are called its life cycle. Then the cycle starts again.
A frog's life cycle has big changes:
- Egg: a frog lays lots of soft, jelly-covered eggs in water.
- Tadpole: a tadpole hatches. It has a tail, lives in water and breathes with gills.
- Froglet: back legs grow first, then front legs. The tail gets shorter and the froglet starts to breathe air.
- Adult frog: the tail is gone. The frog can live on land and in water and can lay eggs of its own.
A marsupial is a mammal that carries its baby in a pouch. A marsupial baby, called a joey, is born tiny, pink and without fur. A newborn opossum is about as small as a bee. The joey crawls into its mother's pouch, drinks her milk and grows fur. When it is big enough, it leaves the pouch, but it stays close to its mother for a while.
Some young animals look a lot like their parents, only smaller, such as kittens, puppies, lambs and chicks. Others look very different, such as tadpoles and caterpillars, and change shape as they grow.
People have a life cycle too: baby, child, teenager, adult.
Worked examples
Order the frog life cycle
Put these in order: adult frog, tadpole, egg, froglet.
- What comes first? The egg.
- What hatches from the egg? A tadpole.
- The tadpole grows legs and becomes a froglet.
- The froglet loses its tail and becomes an adult frog, which lays eggs again.
Answer: Egg, tadpole, froglet, adult frog (and back to egg).
A joey in the pouch
How does a marsupial joey grow?
- It is born very tiny, without fur, and cannot see.
- It crawls into its mother's pouch.
- It drinks milk in the pouch and grows bigger and furrier.
- When it is big enough it comes out of the pouch, then later lives on its own.
Answer: It grows inside its mother's pouch, drinking milk, until it is big enough to come out.
Kitten and cat
How is a kitten like its mother, and how is it different?
- Same: fur, whiskers, four legs, a tail, the same body shape.
- Different: smaller, a newborn kitten's eyes are closed, it drinks milk, and it cannot hunt yet.
Answer: A kitten looks like a small cat but is smaller and cannot do everything an adult can.
Practice check
Have a go, then check your answers. Each answer comes with an explanation.
Answer guide for parents
What hatches from a frog's egg?
A tadpole — A tadpole hatches from a frog's egg.
Which legs does a tadpole grow first?
Back legs — Tadpoles grow their back legs first, then their front legs.
Where does a marsupial joey grow after it is born?
In its mother's pouch — Marsupial joeys grow in their mother's pouch.
Which young animal looks most like its parent?
A kitten — A kitten looks like a small cat. Tadpoles and caterpillars change shape a lot.
What is a life cycle?
The stages a living thing goes through as it grows and has young — A life cycle is the set of stages from young to adult and back again.
Egg, tadpole, froglet, adult frog. Which stage comes first?
egg — A frog's life starts as an egg.
What is the baby of a marsupial called?
joey — Marsupial babies are called joeys.
A caterpillar makes a chrysalis and changes into what insect?
butterfly — A caterpillar forms a chrysalis and changes into a butterfly.
Watch out for
- Children often think a tadpole is a fish or a different animal. It is a young frog at an early stage of its life cycle.
- Some children think all babies look like their parents. Frogs and butterflies change shape completely as they grow.
- Children may think a joey is born big or hatches from an egg in the pouch. Marsupial babies are born live and very tiny, then grow in the pouch.
Tips for parents
- Compare baby photos of your child with photos now and talk about what has changed.
- Draw life cycles as a circle with arrows to show that the cycle starts again.
- Safety: if you watch frogs or tadpoles, check local rules before collecting any; it is often best to observe them in a pond. Wash hands after touching pond water or animals.
Go further
- Make a paper-plate life-cycle wheel for a frog or a butterfly.
- Visit a pond and look for frogspawn or tadpoles without disturbing them.
- Read about another marsupial and draw its joey in the pouch.
About 40 minutes
You'll need
- Pictures (drawn or printed) of the four stages of a frog's life cycle
- Paper plate and a pencil to draw a life-cycle circle
- Photos of family members as babies and as adults (optional)
- Picture books about animals and their young
Key words
- life cycle
- The stages a living thing goes through as it is born or hatches, grows, becomes an adult and has young of its own.
- young
- The babies of an animal. Also called offspring.
- tadpole
- A young frog that lives in water, has a tail and breathes with gills.
- froglet
- A young frog that has legs but still has a short tail.
- marsupial
- A mammal whose tiny babies grow in a pouch on their mother's body.
- joey
- The baby of a marsupial, such as an opossum or a wallaby.
Still tricky?
For parents
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