Twenty Questions

Binary Code in 20Q

Bits can encode everything. How many yes/no questions would it take to identify anything you can think of (e.g., animal, vegetable, music, artist, etc.)? Today you’ll play and discuss the game “20 Questions” in order to think about how binary code can help represent just about anything.

“20 Questions” has been a popular game in the United States for more than a century. Have you played it with your friends or family before? If you haven’t, here’s how the game works:

In the traditional game, one player is chosen to be the answerer. That person chooses a subject (object) but does not reveal this to the others. All other players are questioners. They each take turns asking a question that can be answered with a simple “Yes” or “No.” In variants of the game (see below), multiple state answers may be included, such as the answer “Maybe.” The answerer answers each question in turn. Sample questions could be: “Is it bigger than a breadbox?” or “Can I put it in my pocket?” Lying is not allowed in the game. If a questioner guesses the correct answer, that questioner wins and becomes the answerer for the next round. If 20 questions are asked without a correct guess, then the answerer has stumped the questioners and gets to be the answerer for another round.

Careful selection of questions can greatly improve the odds of the questioner winning the game. For example, a question such as “Is it a machine?” can allow the questioner to cover a broad range of areas using a single question that can be answered with a simple “yes” or “no.” If the answerer responds with “yes,” the questioner can use the next question to narrow down the answer; if the answerer responds with “no,” the questioner has successfully eliminated a number of possibilities for the answer. (Wikipedia)

How has computing affected 20 questions? Well, now we can play against computers using artificial intelligence.

  1. Navigate to

  2. Play 20 Questions against the computer by choosing the language you’d like to play in. Follow the online instructions and see how accurately the computer can guess your chosen subject.

  3. After a few games, click “About Us” in the left side bar of the website. Read the page to learn more about how the program works.

  4. Next, play a game of 20 Questions with a neighbor. Choose the questions you ask in the game strategically.

  5. When you are finished, you will be expected to discuss the following questions:

    • What were some “good” questions? (“good” means “efficient and effective”) Why were those questions good?
    • What were some “bad” questions? (“bad” means “inefficient or ineffective”) Why were those questions bad?
    • How does the choice of questions affect their utility?
    • Who is more effective— or your neighbor?