I was looking through folders on my computer, and came across a document called "The Factor Game," and it occurred to me that in trying to think of some new things to do with my classes, I forgot to play the Factor Game this year when we started talking about factors!
I was so disappointed with myself. Of course, we can play it next week, or any other time, but I just couldn't believe that I had forgotten about it. I'm sure many people know of the Factor Game, or use a version of it, but for those who don't, here it is!
Players start with a simple game board, with the numbers 1-30 (in the past I've alternated between giving them a pre-printed sheet and letting them write their own numbers on their own paper; sometimes I have them play at the whiteboard).
Player 1 chooses a number, and marks it (they might circle it, square it, triangle it, color it etc). Player 2 then marks all of the remaining factors of Player 1's choice.
Player 1 receives points equal to the number they chose, and
Player 2 gets points equal to all of the remaining factors of that number.
Next, Player 2 chooses a number (and gets those points), and Player 1 identifies all of the factors of that number, receiving those points.
Play continues this way until all possible numbers have been used.
*Special rule - players can't choose a number that has no factors available for the other player. If they do, they lose their turn, receiving no points.
When I introduce this game to my classes, we play it on the whiteboard, and I always allow them to go first (the first time). Often, they will choose 30 as their number, since it's the biggest. When I go ahead and mark all the remaining factors of 30 (my points), they are shocked! After the first turn, they have 30 points and I have 42!
(I normally have 2 students record our scores on the board, while 2 others keep running totals on a calculator, but points can all be tallied at the end if you want).
The game continues, alternating turns, until all possible numbers are used, as shown in the "finished game" picture.
The second time we play as a group, I choose 29 as my first number, and they are disappointed to only get 1 point!
We continue to play the second game, and they get a better idea of what makes a good choice.
After our games as a class, I have the students work in partners, and they normally get one or two games played before we stop to discuss at the end of the period. We always talk about what the best and worst first choices are, and bring the idea of prime and composite into the discussion.
I have been playing this game with students for at least 15 years (I think), and every set of students has loved it! I found the game when I was involved with Mathline, so long ago. If you'd like to see the original lesson plan, with extension ideas, click here.
Have you played the Factor Game?