Extrusive Igneous Rocks

About this printable Extrusive Igneous Rocks science reading passage, NGSS-aligned (Grades 3-8)

This NGSS-aligned reading passage introduces 4th-grade students to extrusive igneous rocks, which form when lava cools on Earth’s surface after volcanic eruptions. Students will learn how rocks like basalt, obsidian, and pumice are created and how their properties differ due to quick cooling. The text explains why these rocks often have small or no crystals and highlights fun facts, such as pumice floating on water and Hawaii being formed from basalt. The passage supports comprehension with clear definitions, simple examples, and multiple-choice questions across DOK levels 1–3. Teachers and parents can use this resource to connect Earth science concepts to real-world examples like volcanoes and island formation. With integrated audio support, the passage ensures accessibility for diverse learners. SEO keywords such as extrusive igneous rocks, basalt, obsidian, pumice, and NGSS make this resource easy to discover for classrooms and homeschooling.

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Sample passage and quiz from Extrusive Igneous Rocks

Extrusive Igneous Rocks

Some rocks are born in a flash when hot, melted rock called lava bursts out of a volcano and cools quickly on Earth's surface. These rocks are called extrusive igneous rocks. The word "extrusive" means the rock formed outside, or on top of, the ground.

The journey of these rocks starts deep inside Earth, where intense heat melts solid rock into magma. Pressure pushes the magma up through cracks and openings until it erupts out of a volcano as lava. Once the lava is out in the open air (or underwater), it cools and hardens very fast—sometimes in just minutes!

Because the lava cools so quickly, there isn't time for big crystals to grow. This is why extrusive igneous rocks have tiny crystals or can even look like smooth, shiny glass. Think of it like ice cream: if you freeze it very fast, it stays smooth; if you freeze it slowly, big ice crystals form. Extrusive rocks are like flash-frozen lava popsicles!

There are several cool types of extrusive igneous rocks you might find or see in collections. Basalt is the most common. It is dark gray or black and makes up most of the ocean floors and the Hawaiian islands. Obsidian is shiny, black, and looks like glass. Long ago, people used obsidian to make sharp arrowheads. Pumice is so full of air bubbles that it can float on water! Scoria is rough, red or black, and full of holes from escaping gas bubbles.

You can find extrusive igneous rocks in places with volcanoes, such as Hawaii, Iceland, and Yellowstone National Park. Next time you visit a rock collection or see a volcano on TV, look for these special rocks made from flash-frozen lava!

Interesting Fact: The ocean floor is mostly made of basalt, an extrusive igneous rock!