Two Stages, Billions of Videos: teacher key

How Video Sites Pick Your Videos, grade 11 edition, written for 11th grade. Video sites narrow a huge collection of videos to a few picks by predicting what each viewer will watch. The pages cover the two stages, the signals, the age rules and the controls a viewer can use.

Read the book. Print this page for the key.

Questions and answers

1. According to the passage, which stage of recommendation comes first?
   • Candidate generation (answer)
   • Re-ranking
   • Scoring
2. What did YouTube add to its recommendations in 2012?
   • Star ratings
   • Watch time (answer)
   • Social network links
3. 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
4. What does the COPPA Rule protect?
   • Children under age 13 (answer)
   • Only adults
   • Video makers
5. In this passage, what are "candidates"? "The system generates a much smaller subset of candidates."
   • A much smaller set of 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