18
Lesson 18 of 84 · Westward Expansion
The Pony Express
The Industrial Revolution changed manufacturing. Factories replaced workshops, machines replaced hand tools, and cities grew rapidly as people moved from farms to find jobs.
Key Facts
1
Historians use evidence to support claims.
2
Timelines show events in order.
3
Cause and effect explain why things happen.
Check Your Understanding
Question 1
1 of 2Why do we study history?