Unit 3: Life
Living organisms have evolved into billions of different species since life first emerged over 3 billion years ago. While the complexity of life has increased over time, many species are extinct, which tells us life on Earth is also fragile.

Lesson 3.1

Lesson 3.2

Lesson 3.3

Lesson 3.4
The dinosaurs were wiped out 65 million years ago. Could you survive an extinction event? Time to use your Big History knowledge to put together a survival plan—and consider if we should bring some dinosaurs back to life!
Teaching This Unit
Unit 3 Vocab Guide
Key Unit 3 vocabulary words and definitions.
Activities Guide
How we approach classroom-based activities.
OER Teaching Sensitive Topics in Social Studies Guide
Support for having discussions that are difficult, but meaningful.
Blog: Lesson Plan: Claim Testing
Equip students with the language and practice needed to analyze claims.
Unit 3 Teaching Guide
All the lesson guides you need in one place.