How to teach sudoku

You have been talking to a friend and you mentioned sudoku, of which you are expert in.

“Ah, but I don’t understand math”, this is the most common reply I got from my acquaintances.

A lot of people believe that since there are numbers on the grid, the game is about math.

Of course you know that’s not entirely true (but not entirely false, there is some involvement with the set theory…).

Eventually, you manage to have your friend sit next to you with an easy grid you found online.

Tip: pick a nice and easy sudoku! There’s plenty of grids available, so print out a simmetrical one. They are aesthetically pleasing and appealing.

Give him pencil and rubber: he is controlling the game. Use your own pencil to point at cells while explaining, but let him do the dirty work.

Explain that in every cell goes a number and that in every column, row, and region there must be all numbers from 1 thru 9. There is only one possible solution. That’s all.

First things first, point a cell and ask him which are the candidates for that cell. This is the basic to ensure he will be able to see if a mistake was done.

When he feels confident with this rule, but it happens that it is not enough to solve the sudoku, you can start explaining Full Houses and Last Digits. Address a column almost filled with numbers and ask something as easy as “Which of the numbers 1 to 9 are missing from Column 6?”

Help your friend to narrow down possibilities until you can enter another digit.

Now it’s time to teach the Hidden Single Technique: explain how rows and columns interact with each other. Use the pencil shafts to hide rows and columns as you explain the exclusion processes and show the leftover cells. Let him write the first numbers, and instruct him to double-check that the number does not appear again in the same row, cell, region.

In short time he will be able to solve a basic sudoku on his own, and hopefully learn new tricks to teach you in return.

Have fun in teaching sudoku!



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