- Give the class a phone book.
- Tell the students to pick a business from the phone book, then leave the room so they can keep it a secret from you.
- Come back into the room and tell students that you will find the business only by asking a series of yes or no questions.
- Now, ask those yes or no questions, like does the business start with a letter between A and M.
- Once you found the business, ask students how long it took to find the correct phone book entry.
- Discuss if we could guarantee that we could guess the business within a particular number of guesses.