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Earth Changes Over Millions of Years — Reading Comprehension

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This engaging, audio-integrated science passage for Grade 4-5 students explores how Earth has changed over millions of years. Aligned with NGSS standards, the passage explains important concepts such as weathering, erosion, plate tectonics, and fossils. Students will learn how natural forces like wind, water, and earthquakes shape Earth’s surface, and discover evidence of ancient life through fossils. Real-world examples, clear definitions of key terms, and an interesting science fact enhance understanding. The resource includes a glossary, Spanish translation, reading comprehension quiz, and writing activities that encourage students to connect science with everyday life and analyze cause and effect in nature. Keywords include Earth changes, fossils, weathering, erosion, plate tectonics, and NGSS. Perfect for classrooms looking to build foundational knowledge in earth science with interactive, student-friendly content.

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earth, planet, space, world, universe, outer space, cosmos, galaxy, celestial object, astronomy, earth, earth, earth, earth, earth — "Earth" by WikiImages /
Source: Pixabay.

Geological time is the way scientists measure Earth's incredibly long history. Geological time refers to the billions of years that Earth has existed. Understanding geological time helps us learn how mountains, canyons, and other features formed on our planet's surface.

Earth is about 4.5 billion years old. That number is so large it's hard to imagine! To understand this better, think of Earth's entire history as a 24-hour clock. If Earth formed at midnight, humans wouldn't appear until the very last second before the next midnight. Dinosaurs—the giant reptiles that once lived on Earth—existed between 230 and 66 million years ago. That seems like a long time, but it's only a small part of Earth's total history.

Many of Earth's features took millions of years to form. The Rocky Mountains, a major mountain range in North America, began forming about 80 million years ago and are still being shaped today by wind, water, and weather. The Grand Canyon, a massive valley in Arizona, took about 5 to 6 million years for the Colorado River to carve through layers of rock.

Humans have been on Earth for only about 300,000 years. This is a tiny fraction of Earth's history. Most of the dramatic changes to Earth's surface—like the formation of mountains and the carving of canyons—happened long before people existed.

Interesting Fact: If you could stack all the years humans have existed into a pile of pennies, and stack all of Earth's history the same way, the human pile would be about as tall as a pencil, while Earth's pile would be taller than a 30-story building!

How old is Earth?

About 4.5 billion years oldAbout 300,000 years oldAbout 80 million years oldAbout 230 million years old

When did dinosaurs live on Earth?

Between 230 and 66 million years agoAbout 300,000 years agoAbout 5 million years agoIn the last second of Earth's history

How long have humans existed on Earth?

About 300,000 yearsAbout 4.5 billion yearsAbout 80 million yearsAbout 230 million years

Why does the 24-hour clock analogy help?

It shows how short human history isIt tells the exact age of EarthIt proves dinosaurs were realIt measures the Grand Canyon's depth

What carved the Grand Canyon over time?

The Colorado River cutting through rockDinosaurs walking through the valleyHumans digging with toolsWind blowing away all the dirt

Why are the Rocky Mountains still changing?

Wind, water, and weather shape themDinosaurs are still living thereHumans are building on themThey stopped changing millions of years ago