In this Grade 4 lesson from Science: A Closer Look, Chapter 2: Exploring Ecosystems, students learn what fossils are and how different types form, including molds, casts, imprints, and petrified fossils. Students explore how scientists use fossil evidence to draw conclusions about ancient organisms and past environments on Earth. A hands-on modeling activity reinforces key vocabulary such as fossil, mold, cast, imprint, and nonrenewable resource.
Section 1
Fossils Reveal Earth's Ancient History
Fossils provide evidence of organisms from long ago, forming when sediments bury plant or animal remains. Scientists study different fossil types—molds, casts, imprints, and petrified remains—to understand past environments.
Section 2
Scientists Examine Rock Layers to Date Fossils
Scientists determine fossil ages by their position in rock layers. Oldest fossils appear in bottom layers while younger fossils appear in upper layers, helping scientists track changes over millions of years.
Section 3
Plants and Animals Leave Behind Fossil Fuels
Coal, oil, and natural gas formed from ancient buried organisms. These nonrenewable resources took millions of years to develop but are quickly depleted when burned for energy.
Section 4
Environmental Changes Drive Species to Extinction
When organisms cannot adapt to changes in their ecosystem, they may become endangered or extinct. Fossils of extinct species, like dinosaurs, help scientists understand why certain organisms disappeared forever.
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Section 1
Fossils Reveal Earth's Ancient History
Fossils provide evidence of organisms from long ago, forming when sediments bury plant or animal remains. Scientists study different fossil types—molds, casts, imprints, and petrified remains—to understand past environments.
Section 2
Scientists Examine Rock Layers to Date Fossils
Scientists determine fossil ages by their position in rock layers. Oldest fossils appear in bottom layers while younger fossils appear in upper layers, helping scientists track changes over millions of years.
Section 3
Plants and Animals Leave Behind Fossil Fuels
Coal, oil, and natural gas formed from ancient buried organisms. These nonrenewable resources took millions of years to develop but are quickly depleted when burned for energy.
Section 4
Environmental Changes Drive Species to Extinction
When organisms cannot adapt to changes in their ecosystem, they may become endangered or extinct. Fossils of extinct species, like dinosaurs, help scientists understand why certain organisms disappeared forever.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter