X Marks the Spot Puzzle

I ran across this X Marks the Spot Puzzle several years ago. The goal of the puzzle is to place Xs in the drawing so that a certain set of requirements is met.

After typing up this puzzle with several other brainteasers, I promptly misplaced the computer file before ever using any of the puzzles with my students. Several months ago, I ran across the file and decided I needed to use the puzzles in my classroom and share them here on the blog.

I learned of this challenge from a collection of brainteasers that is no longer online. Luckily, an archived version of the website still exists.

In X Marks the Spot, you are tasked with placing Xs in a drawing to meet certain requirements. Place Xs in the drawing so that:

• exactly two Xs are within the triangle and circle only,
• exactly two Xs are within the square and circle only,
• exactly five Xs are in the triangle, and
• there are a total of ten Xs within the circle.

I plan on using this puzzle with my students in a dry erase pocket to make it easy for them to draw/erase Xs.

MATH = LOVE RECOMMENDS…

I cannot imagine teaching math without my dry erase pockets! They instantly make any activity more engaging and save me countless hours at the copy machine since I can use the same class sets of copies year after year.

Here are my current go-to recommendations:

• 8.5 x 11 Inch Dry Erase Pockets from Puroma
• 11 x 17 Inch Dry Erase Pockets from C-Line Products
• Expo Dry Erase Markers

If you don’t have a classroom set of dry erase pockets, you could also use heavy duty sheet protectors. But, I highly recommend investing in a classroom set of the pockets since they are so much more durable.