Knowing How You Know: teacher key

How to Check If Something Is True, grade 12 edition, written for 12th grade and up. Knowing how you know means asking what kind of claim it is and what evidence could settle it. Eratosthenes, an eclipse test, a faked skull and a moved planet show how checked answers last and how errors get corrected.

Read the book. Print this page for the key.

Questions and answers

1. Which kind of claim can outside evidence settle?
   • One that rests on personal values
   • One you can check (answer)
   • One many people repeat
2. What did Eratosthenes compare to estimate the Earth's size?
   • The Sun's angle in two places (answer)
   • The length of the Nile
   • The size of the Moon
3. Why can a myth about the brain last?
   • Brain scans prove it
   • People see their own shortcomings as proof of unused parts (answer)
   • No one has studied the brain
4. Why was the 1919 eclipse test risky for Einstein's theory?
   • Nobody could see the stars
   • The theory forbade an outcome that could have happened (answer)
   • The eclipse lasted a year
5. How is a proved fraud different from a conspiracy theory?
   • A fraud can be shown with evidence, as Piltdown was with tests (answer)
   • A fraud has no evidence
   • A fraud is always about a secret plot
6. As of November 2026, how many dwarf planets does NASA list?
   • Nine
   • Five (answer)
   • Two

Words

• falsifiability: can be disproved
• tertiary: collected from others
• refute: prove wrong
• conspiracy: secret plot
• bias: leaning one way