Counting Civilizations: teacher key

Aliens and UFOs, grade 11 edition, written for 11th grade. The Drake equation turns a huge question into seven smaller ones, and the Fermi paradox asks why nothing has been found. Here are the numbers, the reports from the sky, and what would count as evidence.

Read the book. Print this page for the key.

Questions and answers

1. What was the Drake equation first written as?
   • A prediction of how many aliens exist
   • A rule about radio signals
   • An agenda for discussion at a 1961 conference (answer)
2. Why does the Drake equation give such a wide range of answers?
   • Many terms are poorly known, and the uncertainty grows with each (answer)
   • It uses only one fact
   • It was never published
3. What is the Fermi paradox?
   • A way to measure starlight
   • The lack of evidence of extraterrestrial civilizations set against the high likelihood that they exist (answer)
   • A kind of radio telescope
4. Why does the Wow! signal stay a puzzle?
   • It was heard every year
   • It was proved to be a comet
   • A one-time signal cannot be checked (answer)
5. According to the Civil Aeronautics Administration, what explained the 1952 Washington radar contacts in almost every instance?
   • A satellite
   • A temperature inversion (answer)
   • A weather balloon
6. What does conjecture mean?
   • A measured fact
   • A guess without firm evidence (answer)
   • A kind of star

Words

• equation: math sentence
• paradox: puzzling contradiction
• conjecture: educated guess
• biosignature: possible life sign
• inversion: layered air