2
Lesson 2 of 84 · World History
The Agricultural Revolution
Primary sources — letters, photographs, diaries, speeches — were created at the time of an event. They give firsthand evidence of what people experienced and thought.
Key Facts
1
Cause and effect explain why things happen.
2
Oral histories preserve community stories.
3
Primary sources come from the time of the event.
Check Your Understanding
Question 1
1 of 2What tool puts events in order?