Predicting What You Will Watch: teacher key

How Video Sites Pick Your Videos, grade 10 edition, written for 10th grade. Video sites pick from a huge collection by predicting what each viewer will watch. These pages explain the stages, the signals the system learns from, the age rules and the controls a viewer has.

Read the book. Print this page for the key.

Questions and answers

1. What did YouTube add to its recommendations in 2012?
   • Star ratings
   • Watch time (answer)
   • Social network links
2. A user sees a video in their recommendations but does not click on it. What does the watch time count as?
   • Zero (answer)
   • One hour
   • Ten minutes
3. What does collaborative filtering do?
   • Recommends a video that a similar user liked (answer)
   • Deletes old videos
   • Blocks all ads
4. Which minimum age do YouTube's terms of service give?
   • 9 years old
   • 13 years old (answer)
   • 18 years old
5. In this passage, what are "candidates"? "The system generates a much smaller subset of candidates."
   • Possible picks (answer)
   • Votes in an election
   • Ads on a page

Words

• algorithm: step-by-step rule
• candidates: possible picks
• autoplay: automatic next video
• signals: pieces of information
• engagement: user actions