Worksheet

Time Clues in a Desert Basin

Use desert field records to compare quick rockfalls and floods with changes that take many years.

Grade 2ScienceInteractive · Printable

Aligned to2-ESS1-1

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Single worksheet
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1 NGSS standard
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13 questions
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Details

Format: Interactive · Printable
Grade: Grade 2
Subject: Science
Question types: Multiple choice, Circle the answer, Sorting, Short answer

About this worksheet

What students practice

Students use time clues to sort Earth changes as quick or very slow.
Students compare records and choose evidence about how long Earth changes take.
Students support a claim that Earth changes can happen over different lengths of time.

How to use

Read the passage together and underline time clues. Have students use the records to answer, then discuss why one day's photos may miss a very slow change.

Curriculum

NGSS standard covered

2-ESS1-1

Use information to show that some Earth events happen quickly and others happen very slowly.

Preview

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Name Date

Time Clues in a Desert Basin

Use desert records to compare how long Earth changes take.

Read the Desert Records

Read the passage. Use its time clues to answer the questions. Choose one answer unless the question says otherwise.

The Basin Watch Station

At a desert basin, a science team studies changes in the land. The team uses cameras, old photographs, and field books. No one stands near falling rocks or rushing water. Cameras record those events from a safe place.

Rockfall record: A camera shows a large rock breaking loose from a steep slope. The rock falls, breaks into pieces, and stops moving within a few seconds.

Flood record: After heavy rain, muddy water rushes through a dry channel. It carries sand and small stones away. This flood lasts about twenty minutes.

Wind record: Wind blows sand against a sandstone rock. Tiny grains wear off its surface. Old photographs and field notes show that the rock's shape has changed a little over many years.

Canyon record: A field book describes the basin's deep canyon. Water has carried away rock and sand during many floods over thousands of years. The canyon did not reach its present depth during just one flood. The team compares these records to learn about Earth's changing surface.

Which recorded change took the least time?

A. The muddy flood passing through the channel
B. The large rock falling and coming to rest
C. The sandstone rock changing its shape
D. The canyon reaching its present depth

Sort the changes by how long they took in the records.

The sandstone rock's shape changingThe flood passing through the channelThe canyon reaching its present depthThe loose rock falling and stopping

Quick: seconds or minutes	Very slow: many years or longer

Nia says, "One flood must have made the whole deep canyon." Which evidence best shows why she should change her idea?

A. The floodwater carried some small stones.
B. The channel was dry before the rain.
C. The team recorded the flood with a camera.
D. The canyon deepened over thousands of years.

Select the TWO observations that are evidence of very slow land changes.

A rock's shape changed a little over many years.A falling rock stopped moving within seconds.A canyon deepened over thousands of years.A flood lasted about twenty minutes.

The flood lasted longer than the rockfall. Does that make this flood a very slow Earth event?

A. No. Minutes are still short compared with many years.
B. Yes. It lasted about as long as the sandstone change.
C. Yes. The flood took many years to carry the sand.
D. No. The flood left the sand and stones in place.

Each time windblown sand hits the sandstone, only tiny grains may wear off. How can the rock's shape change over many years?

A. Large pieces of the rock break off in the wind.
B. The wind stops after the first grain wears off.
C. Many tiny losses can add up as time passes.
D. The rock grows back the grains that wore off.

Check the Team's Evidence

Use the passage and the new camera notes. Think about what each record can and cannot show.

New camera notes
Slope camera: At 9:00, a large rock was on the slope. At 9:01, its broken pieces were at the bottom.
Sandstone camera: Photographs taken one day apart showed no change that the team could see.

The sandstone looks the same in photographs taken one day apart. What is the best conclusion?

A. The wind has stopped wearing the rock.
B. One day may be too short to see its change.
C. The rock changed and then grew back overnight.
D. Wind does not wear grains off sandstone.

What can the two slope photographs show about the rockfall?

A. It took exactly one minute for the rock to fall.
B. It took many years for the rock to fall.
C. It happened before the first photograph was taken.
D. It happened between photographs one minute apart.

Which plan would best help the team check for more slow wear on the sandstone rock?

A. Photograph the same rock from the same spot over many years.
B. Photograph a different rock from a new spot each morning.
C. Photograph the same rock twice during the next minute.
D. Photograph the sky above the rock over many years.

10.

Omar says, "A large rock must take many years to fall because it is big." Which record best checks his idea?

A. The wind record shows tiny grains wearing away.
B. The flood record shows water carrying small stones.
C. The rockfall record shows a large rock falling in seconds.
D. The canyon record shows water removing rock and sand.

11.

The team will record another flood. Select the TWO notes needed to find out how long that flood lasts.

The time when floodwater first arrivesThe color of the camera caseThe number of clouds in one photographThe time when floodwater stops flowing

12.

Which statement goes beyond what these desert records show?

A. Some land changes take much longer than others.
B. Every rockfall in every desert lasts the same time.
C. Water can carry sand away during a flood.
D. A rock can lose tiny grains over many years.

13.

Does Earth's surface always change at the same speed? Use one quick change and one very slow change from the passage to explain. Include a time clue for each.