Timelines of Change
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Learning Objectives
- 1Explain what a timeline is and why historians use it
- 2Read and create a simple timeline using chronological order
- 3Distinguish between BC and AD dates and explain what they mean
- 4Place major historical events on a timeline in the correct sequence
Mini Lesson
A timeline is a visual tool that shows events in the order they happened. Timelines help historians — and learners — understand how the past connects to the present. By reading a timeline, you can see how civilizations rose and fell, how inventions built on each other, and how much the world has changed over thousands of years.
How to Read a Timeline
- Events on a timeline are arranged in chronological order — from the earliest (oldest) on the left to the most recent on the right.
- Each event is marked with a date and a short label.
- The line itself represents the passage of time; longer gaps between events mean more time passed.
- A timeline can cover any span of time — one lifetime, a century, or thousands of years.
BC and AD
- BC stands for "Before Christ" — these dates count backwards from the birth of Jesus. The higher the BC number, the further back in the past.
- AD stands for "Anno Domini" (Latin for "in the year of the Lord") — these dates count forward from the birth of Jesus.
- Example: 3100 BC is much older than 500 BC. 500 AD is older than 2000 AD.
- Some historians use BCE (Before Common Era) and CE (Common Era) instead of BC and AD — they mark the same years.
Decades and Centuries
- A decade is a period of 10 years (e.g. the 1990s decade: 1990–1999).
- A century is a period of 100 years (e.g. the 18th century: 1700–1799).
- A millennium is a period of 1,000 years.
- Tip: the "1700s" = the 18th century; the "1800s" = the 19th century; the "1900s" = the 20th century.
Major Historical Events
- Ancient Egypt begins (~3100 BC) — one of the earliest great civilizations, known for the pyramids and hieroglyphs.
- Roman Empire founded (~27 BC) — Rome grew from a city-state to the largest empire in the Western world.
- Columbus reaches the Americas (1492 AD) — European contact with the Americas begins.
- American Revolution (1776 AD) — the United States declares independence from Britain.
- World War II ends (1945 AD) — the deadliest conflict in human history comes to a close.
- Internet created (1991 AD) — the World Wide Web connects people across the globe.
Tip: For BC dates, think of a countdown — 3100 BC is much OLDER than 27 BC because BC counts backwards toward 0. For AD dates, the higher the number the more recent the event.
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