Earth's Changing Surface — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Earthquakes are slow changes that take millions of years to happen.
Corrected: Earthquakes are fast changes that can happen in seconds or minutes.
Earthquakes are sudden shakings of the ground and are a classic example of a fast Earth change.
2. Fix the sentence:
When a volcano erupts, hot melted rock called sediment flows out.
Corrected: When a volcano erupts, hot melted rock called lava flows out.
Sediment is small bits of weathered rock; the hot liquid rock from a volcano is lava (or magma underground).
3. Fix the sentence:
Landslides happen when rock and soil suddenly grow on the side of a hill.
Corrected: Landslides happen when rock and soil suddenly slide down the side of a hill.
A landslide is the rapid downhill movement of rock, soil, and debris, often after heavy rain or shaking.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A sudden shaking of the ground caused by moving rock under the surface is an earthquake.
Earthquakes are caused when stuck pieces of Earth's crust suddenly slip and release energy as shaking.
2. Hot melted rock that flows out of a volcano is called lava.
When magma reaches the surface during an eruption, it is renamed lava and cools to form new rock.
3. When a river overflows its banks and covers the land with water, it causes a flood.
Floods are fast Earth changes that can move sediment, reshape land, and damage habitats in just hours or days.
4. An opening in Earth's surface where lava and ash erupt is a volcano.
Volcanoes form fast new landforms when erupted lava and ash pile up and cool into rock.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Name two fast Earth changes and one way they are different from slow changes.
Sample answer: Earthquakes and volcanic eruptions are fast Earth changes. They differ from slow changes because they can reshape the land in seconds, minutes, or days, while weathering and erosion take thousands of years.
Grade 4 students should compare the speed of changes to classify them as fast or slow.
2. How can a flood change the surface of the Earth in just one day?
Sample answer: A flood can carry away soil and rocks, knock down trees, and drop mud and sand in new places. In one day, it can carve new paths in the ground and bury old ones with sediment.
Floods cause rapid erosion and deposition, showing how water can quickly reshape the land.