Triple Cross
by Dave Youngs (w/ thanks to Jim Wilson)
In Triple Cross, students are challenged to see how many triangles they can get when they cross a W with three straight lines. They are told that getting seven or fewer triangles is fairly easy; eight is harder; and that the ultimate challenge is to get nine. The student page for this activity has nine W's and can serve as a record sheet.
I found that I had an easier time with this puzzle by using toothpicks instead of drawing lines (and continually erasing them). The toothpicks were not ideal, however, since they wouldn't lie flat. Once I got an answer using toothpicks, I made a record of it with a pencil and a ruler on the worksheet. You may want to use this approach with your students.
Have fun and good luck!
Activity Page
Puzzle Corner
