The Arithmetic of Friendship: teacher key

Friendship, grade 9 edition, written for 9th grade. Friendship has been counted in hours, in circles and in years of life. Here is what the numbers say.

Read the book. Print this page for the key.

Questions and answers

1. According to one study, how many hours does a close friend take?
   • About 50
   • More than 200 (answer)
   • Exactly 90
2. Beyond 150 people, what is the next layer Dunbar names?
   • About 500 (answer)
   • About 15
   • About 5
3. What do the coworker findings suggest about hours and friendship?
   • Coworkers always become best friends
   • Hours alone do not make a friend (answer)
   • Hours are never counted
4. Why do baboon friendship studies take so long?
   • Baboons live in water
   • Baboons refuse to be watched
   • A baboon does not have her first baby until she is 6 or 7 (answer)
5. What does structured mean about social networks?
   • Organized in layers (answer)
   • All the same
   • Built of stone

Words

• freshmen: first-year students
• structured: organized in layers
• grooming: cleaning each other
• acquaintance: someone you know
• correlated: linked together