Sankaku Puzzles (Triangle Area Puzzles)
Sankaku puzzles are a geometric based logic puzzle that focuses on finding the area of a triangle. The goal of each puzzle is to connect three dots to form a triangle with the specified area.
Looking for more printable geometry puzzles for your classroom? Here’s just a few examples of other geometry puzzles I have shared!
Puzzle Source
Sankaku puzzles are the creation of Naoki Inaba, a prolific Japanese puzzle creator. I first discovered these puzzles several years ago on Inaba’s website (which is written entirely in Japanese).
I recently ran across them again, and I decided that they deserved their own entire blog post to hopefully help them get the attention they deserve. These puzzles should be of special interest to geometry teachers or anyone who includes teaching about finding the area of triangles in their curriculum.
Puzzle Instructions
On each grid, connect three of the dots to form a triangle. Each dot must lie at a vertex of the triangle. Additionally, the triangle that is formed must have the area specified below the puzzle.
Triangle Area Puzzles
Inaba includes 42 of these triangle-finding puzzles on his website. They are spread over eight pages which I find really hard to print and use in my math classroom as-is.
I decided to compile the puzzles into a Word document so that they only take four pages instead of the original eight. I also added my English translation of the original Japanese instructions.
I printed these four pages in booklet mode to make a mini puzzle book of the sankaku puzzles for my students.
As you can see inside the booklet, the puzzles start out on 3 x 3 grids, but they quickly increase in difficulty to 4 x 4 grids.
I hope you and your students enjoy hunting for triangles as you solve these sankaku puzzles!
If you like these puzzles, I highly suggest you check out Naoki Inaba’s other math-based logic puzzles. His Zukei Puzzles are another great puzzle for geometry teachers!
Free Download of Sankaku Puzzles
Full Disclosure: These puzzles are the original creation of Naoki Inaba and were originally published on Inaba’s website in Japanese.
Click here to Download
Sankaku Puzzles – Full Size (PDF)
5680 downloads – 313.37 KB
Click here to Download
Sankaku Puzzles – Booklet Version (PDF)
3634 downloads – 240.78 KB
Click here to Download
Sankaku Puzzles (WORD)
2321 downloads – 320.21 KB
Puzzle Solutions
Puzzle solutions are available on a password-protected solution page. I do not openly post the puzzle answer keys because one of my goals as a resource creator is to craft learning experiences for students that are non-google-able. I want teachers to be able to use these puzzles in their classrooms without the solutions being found easily on the Internet.
Please email me at sarah@mathequalslove.net for the password to the answer key database featuring all of my printable puzzles and math worksheets. I frequently have students emailing me for the answer key, so please specify in your email what school you teach at and what subjects you teach. If you do not provide these details, I will not be able to send you the password.
Not a teacher? Go ahead and send me an email as well. Just let me know what you are using the puzzles for. I am continually in awe of how many people are using these puzzles with scouting groups, with senior adults battling dementia, or as fun activities in their workplace. Just give me enough details so I know you are not a student looking for answers to the puzzle that was assigned as their homework!
Pin for Later
Not ready to use this in your classroom just yet? Pin it for later on pinterest!
