### Zendo - For the Math Classroom

If you haven't played Zendo yet, you are missing out on a fun little logic game.  In a nutshell, the "master" is manipulating the playing pieces by following a secret rule that the other players don't know.  The players will each create something and the master will let them know if it follows the rule or not giving counter examples as necessary.  The first player to guess the rule, wins.

My Algebra 1 classes are studying graphing and linear equations and I know this could be an interesting topic to use.

There could be some rules that are created ahead of time or the students could create their own rule.

Some ideas:

• The y-intercept is a multiple of 3.
• The line has a negative x-intercept.
• The line passes through the point (#, #)
• The line is never in the # quadrant.
• The line has an x-intercept that is 1 greater than the y-intercept
• The slope and y-intercept have opposite signs.
• The slope and y-intercept have the same sign.
• If the y-intercept is even, the slope is positive, otherwise the slope is negative.

Put the class into teams and have one group start by sketching the graph of a line.
**Note - all graphs/equations are displayed throughout the round so that students can refer to what did fit the rule and what didn't.

Let's say the rule is "The y-intercept is a multiple of 3."

Group 1
Group 1's example: y = x
Group 1 Guess: The slope must be positive.
Master's Counterexample: y = -x

Group 2
Group 2's example: y = 1/2x
Group 2's Guess: The y-intercept must be 0.
Master's Counterexample: y = x + 3

Group 3
Group 3's example: y = -x + 3
Group 3's Guess: The slope must be either 1 or -1.