Seeds and Growing Plants
FoundationWith water, air and a suitable temperature, a seed sprouts, grows roots and leaves, and one day flowers and bears fruit.
- A seed holds a baby plant and its food.
- Sprouting needs three things: water, air and a suitable temperature.
- Roots take in nutrients below; leaves make food in the sun.
文體小知識：說明文一邊講種子發芽的條件，一邊教你做種豆小實驗，天天記錄觀察。
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1Inside a tiny seed hides a baby plant and its food. When the surroundings are right, the seed wakes: it first swells with water, the seed coat cracks, a white root grows out, and then a tender shoot appears. This is called germination.
2A seed needs three things to sprout: water, air and a suitable temperature. Without water the seed stays dry and asleep; soaked completely in water with no air, it rots; and when it is too cold — mung beans in the fridge, for example — it will not sprout either.
3After sprouting, the seedling keeps growing: roots grow downwards to take in water and nutrients from the soil; the stem grows upwards, lifting the leaves into the sunlight; the leaves make food by photosynthesis. When the plant is grown it flowers; when the flowers fade, fruit forms, and inside the fruit hide new seeds.
4We can run the experiment ourselves: put a few mung beans on wet cotton wool, observe and record every day, and measure with a ruler how many millimetres the sprout has grown. A week later, compare the records and you will see the whole journey — sprouting, rooting and leafing.
1Summary 重點摘要
With water, air and a suitable temperature, a seed sprouts, grows roots and leaves, and one day flowers and bears fruit.
2Vocabulary cards Vocabulary
The grain a plant uses to reproduce, holding a baby plant and food.
When a seed starts to grow and puts out root and shoot.
The outer skin covering a seed and protecting the baby plant inside.
A young plant that has just sprouted.
The process by which leaves use sunlight to make food.
The part a plant forms after flowering, containing seeds.
The nourishment in soil that plants use to grow.
The part of a plant that grows down and takes in water and nutrients.
How hot or cold something is; seeds need a suitable temperature to sprout.
3Step by step Steps
- Step 1: Prepare the materialsTo run a seed-sprouting experiment, prepare the materials first: one clear plastic cup, so you can watch the roots; two layers of cotton wool to hold the seeds; ten mung beans, a few extra as insurance; plus a small water sprayer and a ruler for watering and measuring. Some people think any cup will do, but complete and suitable materials make the experiment go smoothly, keep the observations tidy, and make the measurements accurate.
- Step 2: Lay the cotton and sowSowing is simple, but the water must be judged well. Lay the cotton wool on the bottom of the cup and spray it damp — damp only, never soggy, because seeds soaked in water lack air. Then spread the ten mung beans evenly on the cotton with a little space between them, and place the cup by the window for light and warmth. Some people think more water means faster sprouting, but soaked seeds only rot; dampness is the best state.
- Step 3: Record every dayScientists rely on records, and so should we. Draw a simple chart and observe the beans once a day at the same time, noting the day number, the sprout's length and its appearance — five millimetres on day three, for instance; drawings and photos work too. Some people think memory can retell the experiment, but records are the reliable witness. Comparing the daily records, you can describe the sprouting clearly and find the pattern of growth.
- Step 4: Run a comparisonTo discover what seeds need in order to sprout, run a comparison: three cups of beans — water the first as usual and keep it by the window; never spray the second; give the third water but put it in the cold fridge. Some people think water alone guarantees sprouting, yet after a few days only the first cup sprouts, proving that water and a suitable temperature are both necessary — miss either one and it fails. That is the power of a fair comparison.
- Step 5: Watch the root and leavesSprouting follows an order: around day three to five the white root emerges first and grows downwards; then the tender stem stretches upward, and by about day seven two pale-green leaves open. Some people think leaves come before roots, but the root takes in water and anchors the plant while the leaves catch sunlight to make food — each has its duty. Seeing the order, we understand every part of a plant has its own skill.
- Step 6: Transplant and careA seedling finds only limited food in the cotton; when it is about ten centimetres tall, it is time to move house. Transfer it carefully, cotton and all, into the soil of a flower pot, cover with a thin layer of soil and give a little settling water; then water every other day and keep it in a sunny spot so it grows on. Some people think plants thrive untended, but seedlings need patience. Watching it grow day by day is the most satisfying reward.
4Diagrams Diagrams
5Worked example Example
Example: Yau soaked mung beans completely in a big bowl of water. After three days, the beans neither sprouted nor smelled sweet — they stank. Why?
- Seeds need three things to sprout: water, air and a suitable temperature.
- The beans were soaked completely under water and could touch no air.
- Seeds without air rot, which is why they gave off a bad smell.
- The right way: lay the beans on damp cotton wool — moist but never waterlogged.
- Answer: The beans rotted and stank because they lacked air. Keep the seeds on damp cotton wool with both water and air, place them somewhere warm, and they will sprout smoothly.
6Common mistakes Mistakes
7Quick check Quick check
Q1What three conditions does a seed need to sprout?
Q2What happens to a seed soaked completely in still water?
Q3Which way do roots grow?
Q4What can leaves do?
Q5What hides inside a fruit?
8Recap Recap
- A seed holds a baby plant and its food.
- Sprouting needs three things: water, air and a suitable temperature.
- Roots take in nutrients below; leaves make food in the sun.
- Record daily, and the experiment can be trusted.
- Flowers become fruit, and fruit carries new seeds.