Binary Search

In preparation for looking at searches, you can play the "Dictionary Game," which is played like this:

  1. Have the students pick any word in a standard dictionary. (Make sure you tell them to choose the main word of the article and not one of the other parts of speech or plurals.)

  2. Tell them that you can determine their choice in 20 yes/no questions or less.

  3. Start to perform a binary search.
    E.g.: Is the word before page (midpoint) of the dictionary?

  4. You will have the word within the twenty questions. (Once you get the page number, split the columns.)

This generates many good discussions about efficiency of search methods (linear search versus binary search) and at what point 20 questions would not be enough with a binary search.

In some classes, it may be a good idea for the students to try to guess a word in 20 questions before you do it. They will typically try to narrow down parts of speech and ask for specific words.