Summary
Mystery Doug takes on a real kid's question -- "How do we know the Earth is round?" -- and follows the clues. We know Earth is round from ships dipping over the horizon, its round shadow, and photos taken from space. A quick five-minute watch to spark curiosity and kick off a conversation.
Viewer safety
All ages
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Teaching resources
Discussion questions
Discussion
Doug investigates a question kids really asked: "How do we know the Earth is round?"
- What was Doug's answer to today's question, in your own words?
- What surprised you most about round, or what did you already know?
- What's one thing this makes you want to find out more about?
Quick work-a-long
Words to know: round, horizon, evidence.
Try it: Explain the answer to "How do we know the Earth is round?" to someone at home using these three words, then write down one new question it made you wonder.

