Let’s review what we learned in this unit.

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?

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.

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?

Review this first drawing.

Compare. Find at least two things that are the same on both worksheets.

We noticed that these things were the same in each drawing.

Contrast. Find at least two things that are different on these worksheets.

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.

Get both of your Strange River worksheets.

Compare your worksheets. Only on worksheet number 1, draw rings around things that are different from worksheet number 2.

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.

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.

Video trouble?

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.

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.

Video trouble?

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.

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!

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.

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?

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.

This is one reason it is very hard to know which river is shorter. It is hard to say where the D River ends.

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?

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.

Click play to see where water goes from Devil’s Lake into the D River.

Video trouble?

It is hard to say where Devil’s Lake ends and the D River begins. It could be anywhere along here.

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.

Now is a good time to pause if you want to break this activity into two parts.

Step
01/21

Get a copy of the Shortest River worksheet. Write your name on the worksheet.

Step
02/21

On the D River map on your worksheet, label the Pacific Ocean and the beach. There is a box for each label.

Step
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.

Step
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.

Step
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.

Step
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.

Step
07/21

Now it is time to decide where the source and mouth of each river is. Let’s see what one student thinks.

Step
08/21

Read what this student thinks, and look at their picture.

Step
09/21

Read what this student thinks, and look at their picture.

Step
10/21

Read what this student thinks, and look at their picture.

Step
11/21

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.

Step
12/21

Discuss. Do you agree or disagree with this student? Why?

Step
13/21

Read what this student thinks, and look at their picture.

Step
14/21

Read what this student thinks, and look at their picture.

Step
15/21

Each of these lines on the Roe River is 100 feet apart. How long does this student think the Roe River is?

Step
16/21

Discuss. Do you agree or disagree with this student? Why?

Step
17/21

Where do you think the source and mouth of each river is? Label the source and mouth for each river on your sheet.

Step
18/21

Use the lines on your paper to count how long you think each river is. Remember, each line is 100 feet apart.

Step
19/21

Complete the rest of your sheet.

Step
20/21

Discuss. Which river do your classmates think is the shortest? Do you agree, or disagree?

Step
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!

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

How long is the shortest river?

Image & Video Credits

20 mins

45 mins

Extend this lesson

How long is the shortest river?

Image & Video Credits

Activity Prep

20 mins

45 mins

Extend this lesson

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