Where do flash floods happen?

Where do flash floods happen?
Lesson narration:
English Spanish
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DISCUSS:

Can you think of reasons why one place might flood more than other places?

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DISCUSS:

What is the ground like where you live?

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DISCUSS:

What could turn a puddle into a fast-moving river of water?

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DISCUSS:

How could you figure out which part of Texas gets the most flash floods?

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DISCUSS:

Imagine you're starting with a totally blank map of Texas.

What information would you want to add to your map to help you find Flash Flood Alley?

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Step
01/19
Find a partner — explorers often work in teams. You and your
partner will explore Texas together, share your ideas, and work
together to figure things out.
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Step
02/19
Get your supplies.
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Step
03/19
Cut the Flash Flood Finder worksheet in half on the dotted line.
Now each person has their own Flash Flood Finder.
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Step
04/19
Find the key on your map. It tells you what the marks on the map
mean. Find the waves in the key and on the map. Those waves mean
water. Color the area around the waves blue on the key and the map.
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Step
05/19
Find the numbers on the map that mark places where Flash Flood
Alley might be. If you find reasons that flash floods are likely at one of
these places, you’ll mark them on your Flash Flood Finder.
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Step
06a/19
Here’s the first clue to help you find Flash Flood Alley. Notice that the
parts of the map are different shades of gray. Look at the map’s key.
Discuss with your partner:
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Step
06b/19
The key shows the answer. Darkest gray is the highest land, where
there are tall mountains. Medium gray is lower land, where there are
hills, not mountains. Light gray is where the land is lowest.
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Step
07/19
These pictures show you what you’d see if you traveled to the
highest land, the lower land, and the lowest land on your map. Think
about what would happen in each place after a rainstorm. Discuss:
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Step
08/19
On your map, find where two shades of gray meet. In those areas, a
lower place is next to a higher place. Look for numbers nearby.
Because water runs downhill, flash floods are likely in those locations!
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Step
09/19
On the Flash Flood Finder's key, a triangle symbol means a lower place
is near a higher place. Draw a triangle by each number in a lower
place near a higher place. Flash floods are more likely in those places.
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10/19
On your map’s key, find the line that marks where there are cliffs.
Draw an arrow to show water flowing down the cliff. Work with your
partner & draw arrows for water flowing down cliffs on your map.
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11/19
Flash floods are more likely at the bottom of cliffs and rocky slopes.
On your map, look for numbers that are near cliffs. On your Flash
Flood Finder, put an arrow pointing down by those numbers.
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12/19
On your map’s key, find the shape beside the words “Clay soil.” Use
your yellow crayon to color in the shape. Then find all the areas on
the map that have the word “clay” and color those areas yellow.
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13/19
On your Flash Flood Finder’s key, color the square beside “clay soil”
yellow. On your map, look for numbers near areas with clay soil. On
your Flash Flood Finder, draw a yellow square by those numbers.
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14/19
On your map’s key, find the symbol for “City.” The circle around the
dot shows the city’s pavement. Color the circle red. On your map,
make a red circle the size of the one in the key around each city.
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15/19
On your Flash Flood Finder’s key, color the circle beside “pavement”
red. On your map, look for numbers near areas with lots of pavement.
On your Flash Flood Finder, draw a red circle by those numbers.
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16/19
On the map, find four places marked with an X. Each X marks where
there was a giant rainstorm. Draw a blue cloud over the X in the key
and the Xs on the map.
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17/19
On your Flash Flood Finder’s key, color the cloud beside “Giant
rainstorm” blue. On your map, look for numbers near the rainstorms.
On your Flash Flood Finder, draw a blue cloud by those numbers.
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Step
18/19
Now take a look at your map and your Flash Flood Finder.
Discuss:
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19/19
Here’s what our Flash Flood Finder looks like.
Look at your map and discuss with your partner:
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Slide Image
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river


1 of 17

a long, thin area of water that flows
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flood


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an overflow of water
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flash flood


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an overflow of water that happens very fast
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rain


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water drops that fall from clouds
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storm


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weather that usually includes strong wind and rain or snow
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Slide Image

soil


6 of 17

tiny pieces of rock and other materials that cover the ground
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sandy soil


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a type of soil that has a rough texture; water easily flows through it
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clay soil


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a type of soil that has a smooth texture; water does not easily flow through it
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absorb


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to soak up liquid, like a sponge does
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cliff


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a high area of land with a side that is almost straight up-and-down
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hill


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a high area of land that isn't as tall as a mountain
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mountain


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a high area of land with steep sides
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slope


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where one side is higher than the other
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steep


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something that is very high up on one end and very low at the other end
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plains


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large areas of flat land with few trees
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map


16 of 17

a drawing of a place that shows where things are
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model


17 of 17

a pretend version of something that scientists use when the real thing is too big, small, or complicated to work with
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Lesson narration:
English Spanish

Activity Prep

Print Prep
In this lesson, students explore the phenomenon of flash floods and create an explanation of why these severe weather events are more or less likely in different regions. They specifically attempt to locate and explain a unique region in Texas known as Flash Flood Alley. In the activity, Find Flash Flood Alley, students develop a map to document how land and water interact across the state. Students then use that map to explain how different shapes and kinds of land increase or decrease the chances of rainfall causing a flash flood.
Preview activity
Number of students:

I have a Mystery Pack

Flash Flood Finder printout 1 per pair
Texas Explorer Map printout 1 per student
Crayons
We suggest yellow, red, and blue crayons for each student. Colored pencils also work.
Details
3 crayons per student
Scissors
1 pair per pair
Prep Instructions

We suggest students work in pairs. Homeschool students can work on their own.

Exploration

20 mins

Hands-On Activity

35 mins

Wrap-Up

5 mins

Extend this lesson

Vocabulary

Unit Reading

Activity

Video

Transcripts

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