Grade 3 · Unit 1: Looking after plants
Plant growth and temperature
Do seeds grow faster when it is warm or cold?
Warm and cold
Temperature tells us how hot or cold something is. We measure it with a thermometer. Plants grow best when it is warm, but not too hot.
Most plants grow slowly in the cold. If it is very cold, ice can form inside the leaves and damage them.
Seeds need warmth
Seeds need water and warmth to germinate. In a cold fridge, most seeds grow very slowly or not at all. In a warm room, they start to grow in a few days.
Farmers in Bangladesh sow seeds when the weather is right. Rice likes the warm, wet months, but cauliflower and tomatoes grow well in the cool winter.
An investigation
Put three pots of seeds in three places: a fridge, a classroom and a warm, sunny spot. Give them the same seeds, soil and water. Every two days, measure the height of the seedlings in millimetres.
Keep a table of your results. Then draw a graph. A line graph shows how each plant grew over time.
Too hot!
If it is too hot, plants lose water quickly and wilt. Very high temperatures can kill young plants. Gardeners water plants in the cool morning or evening.
What I learnt
- I know that temperature affects how plants grow.
- I can measure and record plant growth.
- I can describe a fair investigation.