Year 3 Science: Seedlings and growth
Part of the Year 3 Science the life cycle of a flowering plant chapter. Chapter overview · whole chapter on one page
Seedlings and growth
A seedling is a young plant that has grown from a seed. Its root grows down into the soil, and its shoot grows up towards the light. Its first leaves open out.
At first, the seedling uses the stored food from inside the seed. Soon its leaves can make food, using light, water and carbon dioxide. Its roots take in water and nutrients from the soil.
As the plant grows, it becomes a young plant, and then a flowering plant. When it flowers, the plant can be pollinated and make seeds, and the life cycle goes on.
Amira measured one seedling with a ruler, every two days. The table shows its height.
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Key ideas
- A seedling is a young plant that has grown from a seed.
- The root grows down into the soil, and the shoot grows up towards the light.
- At first the seedling uses stored food; then its leaves make food.
- The young plant grows into a flowering plant, and the life cycle goes on.
Method. Look at the picture of the seedling.
- Look at the picture. The part that goes down into the soil is in the soil.in the soil
- Name the part. This part is the root.root
- Write the answer. root
Check. Roots grow down and take in water and nutrients. ✓
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Method. Take the height on day 2 away from the height on day 4.
- Read the two heights. The seedling was 1 cm on day 2 and 3 cm on day 4.1 and 3
- Find the growth. The growth is the later height minus the earlier height.3 − 1 = 2
- Write the answer. 2 cm
Check. 1 + 2 = 3, so the answer is right. ✓
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Method. Compare the growth in each part of the table.
- Day 2 to day 4. The seedling grew 2 cm.2 cm
- Day 4 to day 6. The seedling grew 3 cm, which is more.3 cm
- Choose the days. The most growth was between day 4 and day 6.day 4 and day 6
- Write the answer. day 4 and day 6
Check. 3 is bigger than 2. ✓
Watch out
Watch out: a seedling does not keep using the stored food for ever. Its leaves must make food, and that needs light. A seedling kept in the dark soon grows weakly once its stored food has run out.
Try it at home or school (with a grown-up). With a grown-up, find a flower in a garden or park, and do not pick or touch it. Look at its petals and its centre, using a magnifying glass if you have one. Watch from a safe distance for an insect that visits it. Wash your hands afterwards.
Exam tip
Grown-up tip. Ask: “Where is the middle of the flower? Which parts are the petals?” Let your child find the petals, and say why an insect might visit.
Exercise 4F Seedlings and growth
Method. Think about where a seedling comes from.
- Think about the start. A seedling comes from a seed that has started to grow.from a seed
- Write the meaning. It is a young plant that has grown from a seed.young plant
- Write the answer. Accept any sentence that says a seedling is a young plant that has grown from a seed.
Check. A seedling is a young plant. ✓
Method. Think about the part in the soil.
- Read the chapter. The roots take in water and nutrients from the soil.roots
- Write the answer. roots
Check. The roots take in water and nutrients. ✓
Method. Think about the part that uses light.
- Read the chapter. The leaves use light to make food.leaves
- Write the answer. leaves
Check. Leaves make food in the light. ✓
Method. Think about the food inside the seed.
- Read the sentence. At first the seedling uses the stored food inside the seed.stored food
- Write the answer. stored food
Check. The stored food helps the seedling at first. ✓
Method. Think about what leaves use to make food.
- Read the sentence. Leaves use light, water and carbon dioxide to make food.light
- Write the answer. light
Check. Light is needed to make food in the leaves. ✓
Method. Look at the arrow beside the shoot.
- Read the arrow. The arrow beside the shoot points up.points up
- Name the direction. So the shoot grows up.up
- Write the answer. up
Check. The shoot grows up towards the light. ✓
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Method. Find the row for day 4.
- Find the row. The row for day 4 shows the height.day 4
- Read the height. The height on day 4 is 3 cm.3 cm
- Write the answer. 3 cm
Check. The table says 3 cm for day 4. ✓
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Method. Take the height on day 4 away from the height on day 6.
- Read the two heights. The seedling was 3 cm on day 4 and 6 cm on day 6.3 and 6
- Find the growth. The growth is the later height minus the earlier height.6 − 3 = 3
- Write the answer. 3 cm
Check. 3 + 3 = 6, so the answer is right. ✓
| Day | Height of the seedling |
|---|---|
| day 2 | 1 cm |
| day 4 | 3 cm |
| day 6 | 6 cm |
Method. Work out the growth from day 2 to day 6.
- Read the two heights. The seedling was 1 cm on day 2 and 6 cm on day 6.1 and 6
- Find the growth. The growth is 6 − 1 = 5 cm, not 7 cm.5 cm
- Write the answer. no
Check. 1 + 5 = 6, so Ali is not right. ✓
Method. Add the same growth to the height on day 6.
- Read the height on day 6. The seedling was 6 cm on day 6.6 cm
- Add the growth. It grows another 3 cm, the same as from day 4 to day 6.3 cm
- Find the prediction. The predicted height is the height on day 6, plus the growth.6 + 3 = 9
- Write the answer. 9 cm
Check. A prediction can be checked by measuring again on day 8. ✓
Method. Think about what the stored food does.
- Think about the stored food. The stored food runs out, and the seedling needs more food.runs out
- Give the reason. Its leaves make food from light, so they must keep working to help it grow.leaves make food
- Write the answer. Accept any sentence that says the leaves make food from light, so the plant needs them to keep growing.
Check. Leaves make the food that a growing plant needs. ✓
Method. Follow the life cycle from the seed.
- Start with the seed. The seed germinates and grows into a seedling, then a young plant.germination
- Continue to flowers. The young plant becomes a flowering plant, and its flowers are pollinated.pollination
- End with new seeds. Seeds form in a fruit, and are dispersed to grow into new plants.dispersed
- Write the answer. Accept any answer that links at least three stages, such as germination, flowering and pollination, ending with seeds that are dispersed.
Check. The life cycle goes round from seed to seed. ✓