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Why do trees grow so tall?

Why do trees grow so tall?

Lesson narration:
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Predict:

After 2 weeks, what do you think will have happened to the plant in the dark compared to the plant in the light?

Turn to someone next to you. Tell them your prediction and your reason why.

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Discuss: Why might the plant in the dark have grown taller? Look closely at the plants to see if there are any clues.

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Discuss:

Why do you think the leaves are moving?

plantsmoving

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Discuss:

How can a tree get more sunlight when a lot of other trees are starting to get in its way?

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Discuss:

So now if someone asked you, "Why do trees grow so tall?" how would you explain it to them?

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# Extensions
Below are ideas for extending this topic beyond the activity & exploration which you just completed.
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# Extra Activity: # How to Train a Bean Plant

In this Mystery, we showed photos of a bean plant that we grew here at Mystery Science. We planted the bean in a cardboard box with a hole in it. The bean grew toward the light, snaking its way toward the hole to escape the dark box.

You can duplicate this experiment in your classroom. Just follow these detailed instructions on the website of the Chicago Botanic Garden.

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# Time Lapse Video: # A Year in the Forest

In less than three minutes, this amazing video shows your students how a forest changes over the course of a year. This can be used as an interactive classroom exercise in observation. Ask students to raise their hands when they know what season it is in the forest. Stop the video when enough hands are up, then ask students to explain what clues tell them the season.

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# Video: What will happen if...

Third grader Cameron Wright wondered what a plant would do if she moved the light shining on it. So she decided to experiment.

She got a plant light, planted some peas, and set up a camera to take a picture every 2 minutes. Every 12 hours, she moved the light from one side of the plant to the other. Then she put the pictures together to make a sped up video.

What do you think the video shows? What does the plant do?

Discuss, then watch Cameron's video.

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# Distance Learning: Time Lapse of Grass Growing

Instead of growing Grass Heads, you can try this substitute activity!

Show this time-lapse video of grass seeds growing. [5 seconds = 1 day in real time]

Ask your students to answer the following questions:

  • What happens in the dirt on Day 3 and Day 4?
  • What happens on Day 5 and Day 6?

Have students draw what they notice.

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Image & Video Credits

Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us—we will reply promptly and make things right.

Exploration
4 leaves by Vinayaraj
Forest by OSU Special Collections & Archives
Tree trunk by Tomwsulcer
Trees and sunset by Steve Partridge
Dead sprout by Imgur
Huge tree trunk by Allie_Caulfield
Looking up at tree leaves by David Patte/U.S. Fish and Wildlife
Plant growing in cup by Kirsty
Tree and sunlight by FotoDutch
Few patches of sunlight by Joshua Mayer
Looking up at trees by Rowan, Dick, Photographer
Spiral leaves by Just chaos
Canopy by Phil P Harris.
Ferns in forest by National Park Service
Tree soared into sky by Bradluke22
hole in box by Harris Sisters (Donna)
Dinosaur by LadyofHats
plant in box by Kathy J
Sun shining through trees by Richs5812
dark forest floor by Jim Barton
seeds in a cup by Kirsty
Beans in dark box by Imgur
Light/dark growth by Kirsty
Seed sprouts in cup by Kirsty
sun flowers by ajgarrison3
Calendar by Imgur
Leaves by Hana Kirana
Lesson narration:

Activity Prep

Print Prep

In this lesson, students will learn the importance of sunlight to plants, which is collected by their leaves. In the activity, Grass Head, students make a person out of a paper towel and a popsicle stick with grass for hair! Then, students make predictions about the direction that the grass will grow based on the orientation (standing up or lying down) that they place the Grass Head.

Preview activity

Exploration

25 mins

Extend this lesson

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