What's Happening?
What Scientists Know
All living things have needs. That means there are things they must have to stay alive and grow. People need food, water, and air. Plants have needs too!
Plants Need Water
Plants Need Light
We Can Test Ideas
Let's Try It!
We are going to plan an investigation. That means we will make a step-by-step plan to test our idea. Our idea is: "Plants need water to grow."
This is called a fair test. We only change one thing — the water. We keep everything else the same (the sunlight, the soil, and the pot). That way, we know that water is what made the difference!
What We Found Out
After 10 days, here is what Marcos wrote in his notebook:
| Day | 🌱 Plant A (with water) | 🌱 Plant B (no water) |
|---|---|---|
Day 1 | 5 cm tall, green and straight | 5 cm tall, green and straight |
Day 3 | 6 cm tall, new leaf growing | 5 cm tall, leaves look a little droopy |
Day 5 | 7 cm tall, more leaves | 5 cm tall, leaves are brown at the edges |
Day 7 | 9 cm tall, strong stem | 5 cm tall, very droopy, dry soil |
Day 10 | 12 cm tall, many green leaves | 4 cm (bent over), brown and dried up |
The plant that got water grew from 5 cm to 12 cm. It got big and green! The plant with no water stopped growing. Its leaves turned brown and it bent over.
This tells us something important: water helped the plant grow. Without water, the plant could not stay healthy.
Do You See the Pattern?
Scientists always look for cause and effect. That means they ask: "When I do THIS, what happens?"
In our investigation, the cause was giving water (or not giving water). The effect was what happened to the plant.
| CAUSE (What we did) | EFFECT (What happened) |
|---|---|
| We gave the plant water 💧 | The plant grew tall and stayed green 🌿 |
| We did NOT give water 🚫 | The plant stopped growing and turned brown 🍂 |
This same pattern happens everywhere! When something needs something to live, taking it away causes a change.
| LIVING THING | WHAT IT NEEDS | WHAT HAPPENS WITHOUT IT |
|---|---|---|
| 🌱 Plant | Water | It wilts and stops growing |
| 🐟 Fish | Clean water | It cannot breathe or swim |
| 🧒 You! | Food and water | You feel tired and hungry |
Real-World Connections
People use science to help plants grow! Farmers water their crops every day. If it does not rain enough, farmers use sprinklers or hoses to bring water to their plants. Without water, there would be no food in the grocery store!
Gardeners plan how to take care of their flowers and vegetables. They think about how much water each plant needs. Some plants need a lot of water. Some need just a little. It is like planning an investigation — they watch what happens and make changes!
- 💧 How often will you water?
- 📏 How will you know if the plants are growing?
- 📓 What will you write down to keep track?
Key Vocabulary
- Investigation — A plan to test an idea and find out if it is true.
- Needs — Things a living thing must have to stay alive and grow (like water, food, and air).
- Fair test — A test where you only change one thing and keep everything else the same.
- Observe — To watch carefully and notice what is happening.
- Cause and effect — When one thing (the cause) makes another thing happen (the effect).