What do sunflowers do when you're not looking?
Read-Along Mystery 6 image
What do sunflowers do when you're not looking?
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Optional Activity: Plants on the Move

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.

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Observe and Discuss Part 1

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?

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Observe and Discuss Part 2

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.

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Observe and Discuss Part 3

Your teacher will water the plant regularly. Each time they do, look at the plant’s stem.

DISCUSS:
Are there any changes?

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Extensions

Below are ideas for extending this topic beyond the activity & exploration you just completed.

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Videos

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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Print Prep
Activity Prep

Switch to non-narrated version

In this Read-Along Mystery, Jin plants some sunflowers in a sunny spot and some in a shady spot, watches to see which grow best, and then figures out why. The Mystery includes a short exercise where students stand up and pretend to be sunflowers, turning their faces to the sun as young sunflowers do. You can extend the lesson with the optional activity, Plants on the Move, where students observe that plants respond to light by bending toward the light source.

Preview optional activity

Number of students:
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
Prep Instructions

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.

Setup

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.

Extensions
Download this Mystery to your device so you can play it offline: