You may have been surprised to see the sunflowers in the video bending to face the sun. Plants move much more slowly than people do, so you have to watch over time to see that a plant has reacted to a change. With this simple experiment, you will be able to see for yourself how plants turn to face the light.
Your teacher has set up a plant in the classroom. Look at the plant carefully and notice the direction that its stem (or stems) are growing.
DISCUSS:
Are the stems pointing straight up? Do they lean to one side?
Next, your teacher will put the plant inside of a box, placing it as far from the hole as possible. The plant should be placed so it leans away from the hole, then the box should be closed.
DISCUSS:
What do think will happen? Think about how the sunflowers responded to sunlight.
Your teacher will water the plant regularly. Each time they do, look at the plant’s stem.
DISCUSS:
Are there any changes?
Switch to non-narrated version
Knife
|
1 knife per class |
Scotch Tape
Only needed if your box lets light in.
|
Details
1 roll per class
|
Aluminum Foil
Only needed if your box lets light in.
|
Details
10" per class
|
Cardboard Box (12x12x11")
|
1 box per class |
Soft-Stemmed Plant
|
1 plant per class |
As an optional activity, we suggest having students observe and discuss how plants respond to light.
If you like, you can grow your own experimental plant by planting bean, sunflower, or corn seeds a week before you experiment. Buying a bean seedling or an herb such as thyme will also work.
Get your box ready by cutting a hole that’s about two inches square in one top corner. Hold the box up to the light and check for any other places the light might get in. If there are holes other than the one you cut, tape aluminum foil over them since foil is opaque and it won’t let any light through. Make sure your box is large enough so when your plant is a few inches tall, the whole thing will still to fit inside the box.
Student slideshow: English | Spanish
Teacher printout: English & Spanish
These videos, which show sped-up views of growing plants, will let your students watch each plant’s movements.
This video shows corn seedlings that have been raised in the dark. When the experimenter puts a light bulb above them, they begin bending toward the light, just like the sunflowers in the story do. The video condenses 18 hours into 30 seconds.
This video shows tomato seedlings over several days. In the corner, the word “water” appears whenever the tomatoes are given water. What happens right after the plants are given water?
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