What's Happening? 🌱
After two weeks, the plant on the windowsill was tall, green, and had big leaves. The plant in the closet was short, pale yellow, and droopy. Why do you think they looked so different?
What Scientists Know 🔬
Plants are living things. Just like you need food to grow, plants need certain things to grow, too. One of the most important things a plant needs is sunlight.
Plants Need Sunlight
Plants Also Need Water
Sunlight helps a plant's leaves stay green. When a plant does not get sunlight, its leaves turn yellow or pale. The plant gets weak and cannot grow well.
Let's Investigate! 🧪
Scientists ask questions and then plan tests to find the answers. We can plan our own test to find out: Do plants really need sunlight to grow?
🌱 Let's Try It!
Our question: What happens to a plant that does not get sunlight?
What we need:
- 2 small cups with soil
- 2 bean seeds (the same kind!)
- Water
- A sunny spot (like a windowsill)
- A dark spot (like a closet or a box)
Steps:
- Plant one seed in each cup. Press it gently into the soil.
- Water both cups the same amount.
- Put one cup in a sunny spot. Put the other cup in a dark spot.
- Water both cups the same amount every day. After 10 days, look at both plants and draw what you see!
This is called a fair test (that means we only change one thing). We change the sunlight, but we keep everything else the same — the same soil, the same water, the same kind of seed.
What We Discovered 🌿
After 10 days, here is what we would see in our investigation:
| What We Looked At | ☀️ Plant A (Sunlight) | 🌑 Plant B (No Sunlight) |
|---|---|---|
| Height | Tall — about 15 cm | Short — about 5 cm |
| Color | Green leaves | Yellow or pale leaves |
| Stem | Strong and straight | Thin and droopy |
| Leaves | Big and open | Small and curled |
The plant with sunlight grew much better! This tells us that sunlight helps plants grow. Without it, the plant could not make enough food. It got weak and pale.
Both plants had water and soil. But only one had sunlight. Since sunlight was the only thing that was different, we know that sunlight is what made Plant A grow so much better.
Do You See the Pattern? 🔎
Scientists look for cause and effect. That means: when you do THIS, THAT happens. Let's see this pattern in different places!
| What We Do (Cause) | What Happens (Effect) |
|---|---|
| Give a plant sunlight ☀️ | The plant grows tall and green |
| Take away sunlight 🌑 | The plant grows weak and pale |
| Give a plant water 💧 | The plant stays healthy |
| Stop watering a plant 🏜️ | The plant wilts and dries up |
See the pattern? When a plant gets what it needs, it grows well. When something is taken away, the plant does not grow well. Each thing has a cause and an effect!
You can see cause and effect everywhere. When you eat food, you have energy to play. When you don't eat, you feel tired. Cause and effect!
Plants in the Real World 🌍
People use what they know about plants and sunlight to help plants grow better. Here are some real examples:
Can you design a solution? Imagine you want to grow a small plant in your bedroom, but your room does not have a big window. What could you do to make sure the plant gets enough light?
Think about it! You could move the plant to a brighter room during the day. Or you could use a small lamp near the plant. You are thinking like a scientist and an engineer!
Key Vocabulary 📖
- Sunlight — Light that comes from the sun. Plants need it to make food and grow.
- Investigation — A test or experiment that scientists do to answer a question.
- Fair test — A test where you change only one thing and keep everything else the same.
- Cause and effect — When one thing (the cause) makes another thing happen (the effect).
- Observe — To look at something carefully and notice what you see.