Creating a SuDoku with a class.

Task: To create a 9x9 SuDoku grid.

Quick Task 1:  Using only the numbers 1,2 and 3, arrange them in such a way so that 1,2 and 3 appear only once in each column and row.

Possible solutions

There are quite a few solutions. Younger children could investigate all the different ways you can make a 123 grid.

Ask pupils how they achieved their grids. Explain that using a methodical method of shifting the numbers along will produce a suitable grid.

Quick task 2: Now try the same again using a 4x4 grid and the numbers 1 to 4. What would be the sum value of each row and column? What is the sum total of the entire grid?

At the simplest solution you would find:

Each row and column add to 10. The sum total is 40.

Task 3: With the knowledge of shifting rows, pupils can make a 9x9 grid. Ask the pupils what each column and row would add up to. (45)

However, this is not a SuDoku grid because the smaller blocks of 3x3 do not contain the numbers 1 to 9 only.

The problem can be solved by shifting the next row by more places. How many places will be sufficient to get the first 3 rows correct?

(Answer 3 places)

You can see that the first 3 rows now work perfectly, however this pattern repeats on row 4 and we get another repeat of numbers in all the columns! Can you see the solution to this problem?

By shifting all of rows 4,5 and 6 by one square and rows 7,8 and 9 by two squares, you will avoid any repeats in the columns.

Et voila! The simplest SuDoku grid.