GED and HiSET science — Earth systems and the universe

Earth and space science on the GED and HiSET science tests reaches from the planet's core to the most distant galaxies, and often lands in the news: an earthquake overseas, a hurricane approaching the coast, a wildfire season, a new image from a space telescope. This material covers the parts of the subject that go beyond seasons, tides and the rock cycle, with scenarios drawn from emergency management, construction, park services and news reports.

The quiz starts inside the planet: which layer is liquid, and why the moving molten iron of the outer core produces Earth's magnetic field. It then turns to natural hazards. You compare two earthquakes on the magnitude scale, where each whole step means about ten times more shaking and about thirty-two times more energy, explain why hurricanes draw their power from warm ocean water and weaken after landfall, and match mitigation measures to their hazards: defensible space for wildfires, levees for floods, sirens for tsunamis and building codes for earthquakes. Deep time follows: working out the age of a volcanic rock from the fraction of a radioactive isotope left and its half-life, and how the age of Earth, about 4.5 billion years, is known from meteorites and the oldest rocks. In space, you describe the Sun as a medium-sized, middle-aged star powered by the fusion of hydrogen into helium, explain why a light-year measures distance and what it means to see light that left a star long ago, place the Sun among billions of stars in the Milky Way and the Milky Way among billions of galaxies, and connect the redshift of distant galaxies to the expanding universe and the Big Bang. The last questions weigh human impact: what deforestation does to soil, and why recycling aluminum conserves a nonrenewable ore.

The flashcards review the core, the magnitude scale, hurricane energy, defensible space, half-life, the age of Earth, fusion in the Sun, the light-year, redshift, and sustainable practices.

The written work asks you to explain these ideas in a few sentences and to reason with numbers: a half-life calculation, a magnitude comparison, a preparedness plan for a named hazard. In the oral exam an examiner presents situations one at a time and asks you to explain what is happening and why, then gives brief feedback at the end.

This is independent practice material based on the publicly described content of the two tests; it is not produced or endorsed by GED Testing Service or by ETS.

• Describe Earth's layers and the origin of its magnetic field
• Compare earthquakes on the magnitude scale and explain how hurricanes gain and lose strength
• Match mitigation measures to natural hazards
• Use half-life to date rocks and explain how the age of Earth is known
• Describe the Sun as a star, the meaning of a light-year and the scale of galaxies
• Explain the redshift evidence for an expanding universe
• Evaluate human impacts on land and resources and sustainable practices

Practice material written by Zestly, based on the published descriptions of the GED Science test (ged.com) and the HiSET Science subtest (hiset.org: earth and space science content).