Math = Love: Step Puzzles - An Arithmetic Sequence Puzzle from Naoki Inaba

Saturday, July 13, 2019

Step Puzzles - An Arithmetic Sequence Puzzle from Naoki Inaba

The last time I taught Algebra 1, I used Naoki Inaba's Step Puzzles to introduce the idea of arithmetic sequences. I tweeted about it, but in the craziness of packing up my classroom and house to move last summer they never made it up on my blog.

I was first introduced to the amazing logic puzzles of Naoki Inaba in 2016 when I discovered his area maze puzzles (affiliate link) which have become quite popular.


On his website (which is entirely in Japanese...), Inaba shares a collection of logic puzzles that are PERFECT for the math classroom. I ended up writing a series of blog posts highlighting these puzzles and their potential for use in class in 2016. If you're interested, be sure to check out Volume 1, Volume 2, Volume 3, and Volume 4.

Since then, I've slowly been in the process of translating these puzzles and putting them into a more user friendly format for use in the classroom. So far, I've blogged about Angle Mazes, Zukei Puzzles, and Kazu Sagashi Puzzles.




At the beginning of this month, Simon Gregg tweeted me to ask if I had reformatted Inaba's Step Puzzles to fit more to a page than the original PDF. I had, and this tweet reminded me that I was over a year late in blogging about this!

I like to introduce step puzzles to students by showing them a puzzle and its solution and asking them to figure out the rules of the puzzle.


Because of this problem-solving based introduction to step puzzles, I have not typed out the instructions on the puzzle sheet that I give to students. I have another reason for this. These puzzles are accessible for students as young as elementary school. They are still engaging for middle school and high school students. But, with these age groups, students can be instructed to place numbers in each circle so that each line forms an "arithmetic sequence." This proper vocabulary would likely intimidate an elementary student who could easily tackle these puzzles with an age appropriate introduction.

The puzzles start out quite simply. 


Sometimes my students have used the first puzzle to make an incorrect assumption about how the puzzles work. They assume that 1, 2, 3 is the answer to the first puzzle because 1 + 2 = 3. When really, it is 1, 2, 3 because 1 + 1 = 2 and 2 + 1 = 3. You can check student understanding of this by having them solve the second step puzzle 3, 5, ___. The correct answer is 7. Students with the prior misunderstanding would answer 8.

I've found that once I set students straight from this misunderstanding that they seem to be good to start tackling the puzzles on their own.

The puzzles quickly progress in difficulty. Soon students have to start figuring out where to start solving the puzzle. If students start in the wrong place, the puzzle will seem impossible.


You can download Inaba's original Japanese version of these puzzles here. I've uploaded my paper-saving version here. I'm looking forward to using them with my Algebra 2 students in this upcoming year in our sequences and series unit! 

Before I close out this blog post, check out how Simon Gregg combined WODB (Which One Doesn't Belong) with Step Puzzles!

Image Source: https://twitter.com/Simon_Gregg/status/1146368499885006848

1 comment:

  1. I translated all of these brilliant puzzles a few years ago and made Powerpoints with examles on how to solve them:
    https://www.tes.com/teaching-resource/inaba-puzzles-500-problem-solving-puzzles-11573891

    I deleted my TES account eventually because I was worried about copyright issues but somehow they are still up! Should be OK since they are all available on his website for free in Japanese.

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