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Triangular Numbers Posters and That’s Logical Puzzles

Today I’m sharing some Triangular Numbers Posters with you. It’s January, and I’m still finding new things that need to go up on the walls of my classroom. It’s a bit of an obsession. Don’t believe me? Just take a look at my classroom!

High School Math Classroom Decorations

My Math Concepts class has been working on “That’s Logical” puzzles since we came back to school from Christmas Break in January. These are an out-of-print set of puzzle books from Creative Publications. This is the same publishing company that brought us Algebra with Pizzazz and all the other pizzazz themed books.  From my research, it appears that the company was bought out by McGraw Hill and no longer publishes any books…

For the first few weeks of the semester, we worked through the 1st-4th grade book. I did NOT tell my students that they were working on puzzles meant for 1st-4th graders. Students are given 9 letters (3 X’s, 3 O’s, and 3 V’s) to place in a 3 x 3 grid to satisfy a number of provided “clues.”

The puzzles come in three different levels based on the number of fixed clues that are given.

Here’s an example of a Level 1 puzzle.

That's Logical Puzzles

The puzzles increase in difficulty throughout the book until there are no fixed clues given. Here’s an example of a Level 3 puzzle.

That's Logical Puzzles

I typed up a solution grid template and each student uses a dry erase pocket to solve their puzzle as a daily warm-up.


dry erase pockets

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:

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.

That's Logical Puzzles

My kids were hesitant about these puzzles for the first few days, but after they started understanding how they worked they got really into them. I found that three of these puzzles made the perfect length of warm-up for my math concepts students. Keep in mind, these are students who are in 9th grade but who aren’t ready for 9th grade level math. At my school, this means they aren’t ready for Algebra 1. So, I’m happy to be giving them tasks that are improving their reasoning skills since I believe that reasoning is a crucial prerequisite for high school level math classes (and all math classes for that matter).

That's Logical Puzzles

The first week or two of these puzzles were incredibly easy for my students once they got the hang of it. They should have been easy since they were elementary level puzzles according to the book. The last week or so of puzzles became increasingly tricky because they required higher levels of reasoning. But, they weren’t impossible, so my students still felt a huge sense of accomplishment.

That's Logical Puzzles

This week, we finished off the 1st-4th grade level book and started on the second volume which is designated for 4th-8th graders. These puzzles definitely take a leap in difficulty level between the first volume and the second volume.

Take a look at the first puzzle in the 4th-8th grade book.

That's Logical Puzzles

All of a sudden, we are using the numbers 1-9 instead of letters of the alphabet. And, there are all these weird symbols that we need to know the meaning of. The squares stand for perfect squares. The cubes stand for perfect cubes.

Perfect Square and Perfect Cube Posters

Luckily, I have posters of the perfect squares and perfect cubes on my wall!

E stands for even. If there is an E with a slash through it, it stands for not even. These aren’t on my wall. I kinda assume that my high school students know which numbers are even by now. This isn’t always the case, though…

P stands for prime. I also have a list of prime numbers on my wall.

Prime Number Posters

The last symbol is a triangle which stands for triangular numbers. My students quickly realized I didn’t have the triangular numbers on my wall anywhere.

Triangular Numbers Posters

Well, that was true until yesterday during my planning period when I printed and laminated a set of triangular numbers posters.


drawing of laminator machine with text "laminating recommendations"

A laminator is a MUST-HAVE for me as a math teacher! I spent my first six years as a teacher at a school with a broken laminator, so I had to find a way to laminate things myself.

I’ve had several laminators over the years. I currently use a Scotch laminator at home and a Swingline laminator at school.

I highly recommend splurging a bit on the actual laminator and buying the cheapest laminating pouches you can find!

I printed the triangular numbers posters on yellow paper, and I’ve decided that they remind me a bit of yield signs…

Triangular Numbers Posters

I love that I’ve become the type of teacher with the reputation that every new concept we learn in my math class should be able to be found somewhere on the wall.

My students have needed a lot of help and modeling to tackle these new “That’s Logical” puzzles, but I think after a few days that my students are starting to get it. A few students are refusing to try, but I’m not sure what to do about that. I’m sure our experiences with these puzzles will continue to improve as we continue doing them as a daily warm-up. These puzzles take quite a while longer than the other puzzles, so I’m only allowing time for two of these puzzles each day.

Want to get your hands on these “That’s Logical” puzzles? You can pick up used copies of the puzzle books on Amazon. Here’s the links for Grades 1-4 and Grades 4-8. There used to be some pdf scans of both books floating around on the internet of questionable legality, but they appear to be taken down.

There is a digital version of some of these puzzles that a reader shared that I posted in my Digital Activities Repository post. Check it out!


Monday 4th of October 2021

Thanks for sharing about the "That's Logical" book. I keep checking amazon hoping that the price will become reasonable.


Wednesday 6th of March 2019

I’ve been looking everywhere for the grades 4-8 book. I wasn’t able to find any pdf copies either. Any ideas? Thanks!


Saturday 27th of January 2018

Would love to get ahold of the That's Logical puzzle books - unfortunately the only listing that I can find on Amazon lists prices as $216 each. Any other ideas?


Friday 10th of January 2020

I can't seem to find them online. I hate when books go out of print then disappear!

Sarah Carter (@mathequalslove)

Sunday 28th of January 2018

I mentioned at the bottom of the post that there are some PDF copies of the books online. If you do a search for "That's Logical" Grades 1-4 (and "That's Logical" Grades 4-8), they will show up. I don't want to link to them since they are of questionable legality...

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