Life cycles and traits (grade 3) · lesson

Life cycles

💡 All living things are born, grow, have young, and die, even though the stages look different.

A life cycle is the set of stages a living thing goes through. Then its young start the cycle again.

A butterfly goes egg, then caterpillar, then chrysalis, then adult. In the chrysalis it rests and changes. A frog goes egg, then tadpole, then adult frog. A tadpole has a tail and lives in water.

A bean plant goes seed, then seedling, then grown plant with flowers. The flowers make pods with new seeds.

The stages are not the same for every living thing. But all of them begin life, grow, have young, and die.

🧠 Let's work it out

Find where the living thing is now.
Then ask what stage comes next.
A caterpillar inside a still, hard case is in its chrysalis.
The next stage is the adult butterfly.

What do you think comes next?

life cycle: the stages a living thing goes through, again and again
larva: the young stage of an insect, like a caterpillar
pupa: the resting stage when an insect changes, like a chrysalis
tadpole: a young frog with a tail that lives in water

Traits from parents

💡 Many traits, like eye color and fur color, are passed from parents to their young.

A trait is something about a living thing, like its fur color or ear shape.

Many traits come from parents. A puppy can have brown fur like its mom. A sunflower has yellow petals like the plant its seed came from.

These are called inherited traits. A living thing is born with them. It cannot pick them or learn them.

🧠 Let's work it out

Ask: was it born with this trait?
Eye color, ear shape, and petal color are there from the start.
So they are inherited.
A scar is not. It came from a fall.

What do you think comes next?

trait: something about how a living thing looks or acts
inherited: passed down from parents

Traits shaped by living

💡 Food, light, exercise, and learning can change some traits during a living thing's life.

The environment is everything around a living thing. It is food, water, light, and weather.

The environment can change some traits. A plant with no light grows short and pale. A kitten that eats more gets heavier. Flamingos turn pink from the shrimp they eat.

Some things are learned. A dog learns to sit. A girl learns to read. Nobody is born knowing how.

🧠 Let's work it out

Look for what is different.
Two plants came from the same parent.
One grew in sun and one grew in a dark closet.
The parent is the same, so the dark place made the change.

What do you think comes next?

environment: everything around a living thing
learned: something you are taught or practice, not born with