How much earth science is on the GED?

Earth and space science is about 20 percent of the Science test.

What causes the seasons?

Earth's roughly 23.5-degree axial tilt, which changes how directly sunlight strikes each hemisphere through the year.

GED Earth and Space Science Practice

Earth and space science is about 20 percent of the GED Science test — the smallest share, and the most fact-driven. A short study session here often produces the fastest score gain.

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Which process moves water from the ocean surface into the atmosphere?

Earth's structure and the rock record

Earth has four layers: crust, mantle, liquid outer core, and solid inner core. The circulating molten metal of the outer core generates the planet's magnetic field. Tectonic plates float on the mantle, and earthquakes, volcanoes, and mountain ranges concentrate at their boundaries.

In undisturbed sedimentary layers, newer material sits on top of older material. This principle of superposition lets geologists read a sequence of events out of a cliff face, and it is a favorite setup for GED diagram questions.

Water, weather, and climate

The water cycle moves through evaporation, condensation, precipitation, and collection, with transpiration from plants and infiltration into soil as additional paths. Weather questions usually involve air masses: when a cold front pushes under warmer air, the warm air rises, cools, condenses, and produces clouds and storms.

Climate questions center on greenhouse gases. Carbon dioxide and methane trap outgoing infrared energy, and rising concentrations correlate with rising global average temperature. Expect to interpret a graph rather than recall a number.

Resources and space

Renewable resources such as wind, solar, and hydro replenish on a human timescale. Fossil fuels do not. Questions often ask you to weigh a tradeoff rather than declare one option best.

For space, the essentials are short: Earth's seasons come from its axial tilt, not its distance from the Sun; moons orbit planets while planets orbit stars; and the phases of the Moon result from the changing angle of sunlight we see from Earth.

Frequently asked questions

How much earth science is on the GED?: Earth and space science is about 20 percent of the Science test.
What causes the seasons?: Earth's roughly 23.5-degree axial tilt, which changes how directly sunlight strikes each hemisphere through the year.