Lesson 69 of 84 · Earth's History
Lesson⭐ 30 XP🌋 Rock RealmThe Geologic Time Scale (Part 2)
Earth's History.
🎯 Your mission
Understand the idea. Then look for it everywhere.
⚡ The twist
Weather isn't random — it's just complicated.
Mind = Blown
🌋 There are 1,500 active volcanoes on Earth right now.
Make a hypothesis first
Before you observe: what shape will it leave?
What You'll Learn
The geologic time scale divides Earth's 4.6-billion-year history into eons, eras, and periods. Scientists mark the boundaries using major events like mass extinctions and the appearance of new life forms recorded in the rocks.
Key Words
Tap a word to see its definition.
Steps
Review the background information on Earth's History before starting.
Create a model of the water cycle in a bowl: place warm water in a bowl, cover with plastic wrap, put ice on top, and observe condensation and precipitation.
Compare the before and after states.
Write your conclusion: did the results match your hypothesis? What would you change next time?
Check Your Understanding
Question 1
1 of 3What is erosion?
Where you see this in real life
This is shaping the ground you walk on, slowly, every single day.
Stretch Challenge
Try this in real life this week.
Find a rock outside and try to guess how old it is.
For the dinner table
“What's the slowest change you can think of?”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
Share this experiment
Send it to a parent who's looking for a 10-minute kitchen science win.
Checkout complete lesson on Earth's History for 4th Grade
Get the full Earth's History track as a printable PDF — all lessons, worksheets, and answer keys.