Volcanoes: Mountains That Can Explode

Lexile: 860 | Grade: 5

Passage

Most mountains stay still. But some have the power to shake, rumble, and erupt. These are volcanoes—openings in the Earth’s surface where molten rock, gases, and ash escape from deep underground.

Volcanoes form near cracks in the Earth’s crust, often where tectonic plates meet. Beneath the crust is a layer called the mantle, where rock melts into **magma** because of extreme heat and pressure. When magma rises to the surface, it can cause an eruption.

Some eruptions are gentle, with lava flowing slowly down the sides. Others are violent, sending ash clouds high into the sky and covering nearby land in thick layers of rock and dust.

Volcanic eruptions can be dangerous. They can destroy homes, block sunlight, and even change weather patterns. But volcanoes also help create new land. Many islands, like Hawaii, were formed by underwater eruptions over millions of years.

Scientists called **volcanologists** study volcanoes to better understand how they work and to warn people when one might erupt. Today, they use tools like seismometers to measure ground movement and satellites to track changes in temperature and shape.

Although volcanoes can be powerful and scary, they are also a natural part of Earth’s cycle of change. They remind us that the ground beneath our feet is always moving—even when we can’t feel it.

Questions

Q1: What is the main idea of the passage?

  • A. Volcanoes are mountains that people can climb for fun.
  • B. Volcanoes are powerful natural features that can both destroy and create land.
  • C. Most volcanoes are not dangerous and rarely erupt.
  • D. Volcanoes only exist on islands like Hawaii.

Q2: How are volcanoes formed?

  • A. By wind blowing dirt into mountains
  • B. By water freezing in cracks in the ground
  • C. By magma rising through cracks in the Earth’s crust
  • D. By earthquakes shaking up the soil

Q3: What is magma?

  • A. Frozen rock from the ocean
  • B. Hot, melted rock found below the Earth’s surface
  • C. Dust that comes from clouds
  • D. The same thing as lava found in the sky

Q4: Why do scientists study volcanoes?

  • A. To keep people safe by predicting eruptions
  • B. To stop eruptions from happening
  • C. To take pictures of lava for fun
  • D. To make earthquakes stronger

Q5: What can you infer about volcanic islands like Hawaii?

  • A. They are likely to freeze over often.
  • B. They were created by eruptions long ago.
  • C. They are not connected to tectonic plates.
  • D. They are made from sand blown by wind.

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Answers & Reasoning

Q1: What is the main idea of the passage?

✅ Correct Answer: B

💡 Reasoning: The passage explains both the dangers and benefits of volcanoes, highlighting their power and role in shaping Earth.

Q2: How are volcanoes formed?

✅ Correct Answer: C

💡 Reasoning: The passage states that volcanoes form where magma rises through cracks in the crust, especially near tectonic plate boundaries.

Q3: What is magma?

✅ Correct Answer: B

💡 Reasoning: The passage defines magma as melted rock beneath Earth’s surface caused by heat and pressure.

Q4: Why do scientists study volcanoes?

✅ Correct Answer: A

💡 Reasoning: The passage says volcanologists study volcanoes to understand them and warn people before they erupt.

Q5: What can you infer about volcanic islands like Hawaii?

✅ Correct Answer: B

💡 Reasoning: The passage states that islands like Hawaii were formed by underwater volcanic eruptions over millions of years.