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How long is the shortest river?

How long is the shortest river?
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Let’s review what we learned in this unit.
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Rivers flow from high places to low places. Study this paper mountain. Can you spot any places where two rivers come together, just like the Missouri River and the Milk River?
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Here are two places we saw rivers coming together as they go downhill. You might have seen rivers come together on your paper mountain, too.
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Rivers erode the land. The land breaks into rocks. Rocks break down into sand. Do you see any rocks breaking down and falling into the Milk River in this picture?
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Review this first drawing.
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Compare. Find at least two things that are the same on both worksheets.
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We noticed that these things were the same in each drawing.
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Contrast. Find at least two things that are different on these worksheets.
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Here are two things we noticed that are different. We drew rings around the things that are different on the first worksheet. You’re going to do this same thing with your worksheets now.
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Get both of your Strange River worksheets.
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Compare your worksheets. Only on worksheet number 1, draw rings around things that are different from worksheet number 2.
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Only on worksheet number 1, add source and mouth labels to the rivers. The source is the start of each river, and the mouth is the end.
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There is another special river that flows into the Missouri River. It is called the Roe River. It is near Great Falls, Montana, USA. Click play to fly to the Roe River now.
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Video trouble?
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This is the entire Roe River! Some people think it is the shortest river in America. The picture shows where some people think the source is.
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It is only about 200 feet / 60 meters from source to mouth. Click play to see where water flows from the source, to the mouth, and out into the Missouri River.
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Video trouble?
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The Roe River is definitely a short river. But some people think a different river is even shorter. Let’s go to that river now.
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This is Lincoln City, Oregon, USA. There is a river here called the D River. Many people think the D River is the shortest river!
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This is the entire D River. Some of the time, it is about 400 feet / 120 meters long. The source is near the parking lot. The mouth is at the Pacific Ocean.
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Discuss.The Roe River is 200 feet long. Some of the time, the D River is 400 feet long. Why do you think some people think the D River is shorter?
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Sometimes, the D River is shorter. Sometimes, the ocean comes up high on the beach. Then, the D river is only about 100 feet / 30 meters long.
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This is one reason it is very hard to know which river is shorter. It is hard to say where the D River ends.
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It is also hard to say where each river starts. The water for the Roe River comes from a small pool of water. Discuss. Where do you think the pool ends and the Roe River begins?
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The water for the D River comes from Devil’s Lake. The next video shows you how the water moves from the lake to the river.
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Click play to see where water goes from Devil’s Lake into the D River.
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Video trouble?
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It is hard to say where Devil’s Lake ends and the D River begins. It could be anywhere along here.
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It is hard to say how long a river is if you aren’t sure where the river starts and ends. But that is what you’re going to try to do.
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Now is a good time to pause if you want to break this activity into two parts.

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Step
01/21
Get a copy of the Shortest River worksheet. Write your name on the worksheet.
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02/21
On the D River map on your worksheet, label the Pacific Ocean and the beach. There is a box for each label.
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03/21
Remember: the ocean can be higher or lower on the beach. That makes the D river shorter and longer. Your worksheet shows the river at its longest.
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04/21
This photo of the Roe River was not taken from up above. You’ll have to imagine what the Roe River looks like from above.
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05/21
There is a small island between the Roe and Missouri Rivers. Two little bridges go out to it. Find the island. Draw a line to connect the island and its label.
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06/21
Find the pool of water that goes into the Roe River. Draw a line to connect the pool of water to its label.
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07/21
Now it is time to decide where the source and mouth of each river is. Let’s see what one student thinks.
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08/21
Read what this student thinks, and look at their picture.
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09/21
Read what this student thinks, and look at their picture.
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Read what this student thinks, and look at their picture.
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Each of these lines on the rivers is 100 feet apart. Use the pictures to figure out how long this student thinks each river is, from source to mouth.
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12/21
Discuss. Do you agree or disagree with this student? Why?
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13/21
Read what this student thinks, and look at their picture.
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Read what this student thinks, and look at their picture.
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15/21
Each of these lines on the Roe River is 100 feet apart. How long does this student think the Roe River is?
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Discuss. Do you agree or disagree with this student? Why?
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Where do you think the source and mouth of each river is? Label the source and mouth for each river on your sheet.
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18/21
Use the lines on your paper to count how long you think each river is. Remember, each line is 100 feet apart.
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19/21
Complete the rest of your sheet.
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20/21
Discuss. Which river do your classmates think is the shortest? Do you agree, or disagree?
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21/21
Experts don’t agree on the answer to this question. Some think one of these rivers is the shortest. Some think other rivers are even shorter. There is no easy answer!
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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.

Other
All illustrations by Alex Kalomeris
D River Aerial by Frank Cavezza / News Guard
D River High Tide Aerial by Surfrider Foundation
Devil's Lake Aerial by my WheelEstate and a Drone
Giant Springs State Park by Fouled Anchor Photography
Milk River Alberta Badlands by Pictureguy
River Video by Mikko
Credits

Activity Prep

Print Prep

To use alternate supplies, go to the previous version.
In this performance task, students explore the difficulty of measuring the length of a river. Figuring out which river is the shortest river is difficult to do if you can't decide where a river starts or ends.

After a review of the Work of Water unit, students will learn about two rivers that are each possibly the shortest rivers in the United States. Then, they map those rivers out and attempt to determine which river is the shortest.

The activity can be broken into two parts: the introduction, and the activity. We suggest a point to do this in the lesson itself.

Preview activity
Number of students:
Shortest River printout 1 per student
Prep Instructions

Before starting this lesson, review the unit Teacher Guide for an overview of the Work of Water Anchor Layer.

Unit Review

20 mins

Hands-On Activity

45 mins

Extend this lesson