Year 3 Science: Germination: what a seed needs
Part of the Year 3 Science the life cycle of a flowering plant chapter. Chapter overview · whole chapter on one page
Germination: what a seed needs
A bean seed is a tiny living package. It has a seed coat on the outside, which protects it. Inside, there is stored food, and a tiny young plant with a root, a shoot and leaves.
Germination is when the seed begins to grow. To germinate, a seed needs:
- water, which soaks into the seed and makes it swell;
- a suitable temperature, which means a warm place, not a very cold one;
- air, which the seed needs in order to grow.
A seed does not need soil to germinate. At first it uses the stored food inside it. The soil is needed later, when the young plant needs nutrients.
Priya and Noah set up a fair test with three dishes. Each dish has 10 bean seeds. Dish A is damp and warm. Dish B is dry and warm. Dish C is damp and cold. The table shows the results after 7 days.
| Dish | Water | Temperature | Seeds that germinated (out of 10) |
|---|---|---|---|
| A | damp | warm | 9 |
| B | dry | warm | 0 |
| C | damp | cold | 3 |
Key ideas
- A seed needs water, a suitable temperature and air to germinate.
- A seed has a seed coat, stored food and a tiny young plant inside.
- A seed does not need soil to germinate; it uses its stored food at first.
- In a fair test, only one thing changes at a time.
Method. Look for the one thing that is different between the two dishes.
- Read dish A. Dish A is damp and warm.damp, warm
- Read dish B. Dish B is dry and warm. Both dishes are warm, so only the water is different.dry, warm
- Name the one thing. The one thing that is different is the water.water
- Write the answer. water
Check. Only the water changes between A and B. ✓
Watch out. The temperature is the same in dishes A and B, so it is not the thing that changes.
Method. Take the seeds that germinated away from the seeds in the dish.
- Read the two numbers. Dish A had 10 seeds, and 9 of them germinated.10 and 9
- Subtract. The seeds that did not germinate are the total, minus the ones that germinated.10 − 9 = 1
- Write the answer. 1
Check. 9 + 1 = 10, so the answer is right. ✓
Method. Take the smaller number away from the bigger number.
- Read the two numbers. Dish A had 9 seeds germinate, and dish C had 3.9 and 3
- Find the difference. The difference is how many more seeds germinated in dish A.9 − 3 = 6
- Write the answer. 6
Check. 3 + 6 = 9, so the answer is right. ✓
Watch out
Watch out: a seed can be damp and still not germinate well if it is cold. Dish C was damp, but it was cold, and only 3 seeds germinated. Both water and warmth are needed.
Try it at home or school (with a grown-up). With a grown-up, put 10 bean seeds on damp cotton wool in a clear cup on a windowsill. Put 10 more on damp cotton wool in a cool cupboard. Keep both damp. Each day for a week, count how many seeds have started to grow, and write the numbers in a table. Wash your hands afterwards.
Exam tip
Grown-up tip. Ask: “What is different about the two cups? What is the same?” Let your child count the seeds that have started to grow each day, and write the numbers in a table.
Exercise 4E Germination: what a seed needs
Method. Think about what helps a seed to swell and grow.
- Think about water. A seed needs water to soak into it.water
- Think about warmth and air. A seed also needs a suitable temperature and air.warmth and air
- Write the answer. Accept any two of: water, warmth, air.
Check. Water, a suitable temperature and air are needed to germinate. ✓
Method. Read the table.
- Read the water column. Dish B is marked dry in the water column.dry
- Name the letter. So the dry dish is dish B.B
- Write the answer. B
Check. Dish B had dry cotton wool. ✓
Method. Read the table.
- Read the temperature column. Dish C is marked cold in the temperature column.cold
- Name the letter. So the cold dish is dish C.C
- Write the answer. C
Check. Dish C was cold. ✓
Method. Think about what soaks into a seed.
- Read the sentence. Water soaks into the seed and makes it swell.water
- Write the answer. water
Check. Water makes a seed swell. ✓
Method. Think about the food inside a seed.
- Read the sentence. The stored food inside the seed helps the young plant at first.stored food
- Write the answer. stored food
Check. The stored food helps the seed to start growing. ✓
Method. Read the label under each dish.
- Read the labels. Dish A is labelled damp, warm.damp, warm
- Name the letter. So the dish that is damp and warm is dish A.A
- Write the answer. A
Check. Dish A had damp cotton wool and was warm. ✓
Method. Read the results.
- Read the results. Dish B had 0 seeds that germinated out of 10.0 germinated
- Name the letter. So dish B gave no seeds that germinated.B
- Write the answer. B
Check. Dish B was dry, and none of its seeds germinated. ✓
Method. Read the height of the bar for dish C.
- Find dish C. The bar under C is labelled with its value.bar C
- Read the value. The label on the bar for dish C says 3.3
- Write the answer. 3
Check. The bar for dish C shows 3 seeds. ✓
Method. Find the tallest bar on the chart.
- Compare the bars. The bar for dish A is the tallest.tallest A
- Name the letter. So dish A had the most seeds germinate.A
- Write the answer. A
Check. Dish A had 9 seeds germinate. ✓
Method. Take the seeds that germinated away from the 10 seeds in the dish.
- Read the two numbers. Dish C had 10 seeds, and 3 germinated.10 and 3
- Subtract. The seeds that did not germinate are the total, minus the ones that germinated.10 − 3 = 7
- Write the answer. 7
Check. 3 + 7 = 10, so the answer is right. ✓
| Dish | Water | Temperature | Seeds that germinated (out of 10) |
|---|---|---|---|
| A | damp | warm | 9 |
| B | dry | warm | 0 |
| C | damp | cold | 3 |
Method. Add the numbers that germinated in the three dishes.
- Read the three numbers. The dishes had 9, 0 and 3 seeds germinate.9, 0, 3
- Add them together. The total is the seeds that germinated in all three dishes.9 + 0 + 3 = 12
- Write the answer. 12
Check. The total of the three dishes is 12. ✓
Method. Check what was different about dish B.
- Read the test. Dish A and dish B were both warm. Only the water was different.both warm
- Decide. Because the warmth was the same, the warmth did not cause the result. The answer is no.not fair
- Write the answer. no
Check. Only the water changed between A and B. ✓
Method. Think about what a damp, warm dish gives the seeds.
- Think about the conditions. The seeds in dish A have water and warmth.water and warmth
- Make the prediction. So more seeds may germinate, and the young roots and shoots may grow longer.more grow
- Write the answer. Accept any prediction that says more seeds will start to grow, or the young roots and shoots will get longer.
Check. A prediction can be checked by counting again after a week. ✓
Method. Think about what seeds need first.
- Think about water. A seed needs water to soak in and make it swell.water
- Give the reason. Dish B was dry, so the seeds could not soak in water and start to grow.dry
- Write the answer. Accept any sentence that says dish B was dry, so the seeds had no water to soak in and start to grow.
Check. Water is one of the three things that a seed needs. ✓