Lava Lesson for Kids: Definition & Facts

Instructor: Jennifer Lowery

Jennifer has taught elementary levels K-3 and has master's degrees in elementary education and curriculum/instruction and educational leadership.

Lava is molten rock that escapes through a volcano. In this lesson, learn about what lava is made of, how it escapes, and different types of lava flows, and where they occur on Earth.

What is Lava?

If you could dig a tunnel deep inside of the Earth, you would eventually come to an inner core that is scorching hot! This inner core contains rock that is molten, which means it is so hot that it has become a liquid. When this molten rock is inside the Earth, it is called magma. But once it escapes and come onto the Earth's surface, it is called lava. There are different types of lava, and those categories are based on the type of rocks that are found in lava flows.

Scientists study lava flows to determine what types of molten rock the lava is made of.
Scientist testing lava

Escaping Lava

So just how does magma escape from inside the Earth and become lava? This molten rock emerges through an opening in the Earth called a volcano. Volcanoes occur when pieces of the Earth, called plates, move and either come together or drift apart.

When you think of a volcano, you probably think of a large cone-shaped mountain with a hole in the top, right? There are other types of fractures in the Earth where lava flows like fissure vents, which are relatively flat. Shield volcanoes are raised areas of land, but they are not as high and are much wider than other volcanoes.

Lava can escape from different types of openings in the Earth.
erupting lava flow

Lava Flows

So how does lava flow? The answer depends on something called viscosity. Viscosity is a word used to describe how thick or thin the lava is. Thicker lava has a higher viscosity and will flow more slowly. This lava creeps along the Earth's surface and is not very dangerous to humans. Thinner lava is lava that has low viscosity and can easily move along surfaces and through volcano vents. Low viscosity lava is the type that can cause spectacular eruptions, and can be quite dangerous!

Lava with lower viscosity can spread quickly across the surface of the Earth.
cascading lava flow

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