Sudoku for kids

1. 01Choose size, symbols and difficulty. The preview shows the first sheet right away, and with a click on “Solutions” the solution sheet too.
2. 02Set how many sudokus go on a sheet and how many sheets you need. If you do not like the puzzles, click “New puzzles”.
3. 03Download the PDF and print it at “Actual size”. At the bottom of every sheet you find the No., size and level (and “not symmetric” if you turned symmetry off). With these you get exactly these puzzles back.

What it is. A sudoku generator for paper, not for playing on screen. Every row, every column and every thick box has each symbol exactly once. 4 × 4 has boxes of 2 × 2 squares, 6 × 6 has boxes of 2 rows by 3 columns, 9 × 9 has boxes of 3 × 3.

Exactly one solution, no guessing. Before a puzzle goes on the sheet, the tool solves it itself, the way a person would: step by step, using only conclusions that are certain. If that does not fully work, the puzzle does not go on the sheet. A second solver also tries every possibility and confirms that there is exactly one solution. So guessing is never needed at any level.

The levels say which steps the puzzle needs. Easy: only one symbol fits in a square, or a symbol fits in only one place in its row, column or box. Medium: adds candidate pairs (two squares in a row, column or box where only the same two symbols fit) and elimination across box and row. Hard, only for 9 × 9: adds hidden pairs, triples, X-Wing and Y-Wing. How hard a puzzle feels is different for every child; the level only describes the steps needed.

Why 4 × 4 only has Easy. In 16 squares the two simple steps are always enough. The tool has worked through all 13,579,680 unique 4 × 4 puzzles, none needs more. For 6 × 6 only a small share of puzzles needs a Medium step, depending on the settings about one in 170 (without symmetry) to one in 500 (symmetric); finding them takes a bit longer there.

How many symbols are given. Easy leaves more than needed: at least 6 of 16 for 4 × 4, at least 15 of 36 for 6 × 6, at least 36 of 81 for 9 × 9. Medium and Hard leave only as many as needed for exactly one solution at that level. The preview shows the number for each sudoku.

Shapes are for children who cannot read numbers or letters yet: circle, square, triangle and star for 4 × 4, plus heart and diamond for 6 × 6. The child draws the right shape in the empty squares. The tool draws the shapes itself as lines, easy to tell apart even in black and white. There are no shapes for 9 × 9. Custom symbols are exactly as many different letters or digits as the grid is wide, such as FROG for 4 × 4 or GARDEN for 6 × 6.

The No. The same No. and the same size, level and symmetry give the same puzzles. Symbols, heading, rule and name line do not change the puzzles, only how they look. So you can print the same sheet with numbers for some children and with shapes for others. This applies to this version of the tool; if you want to keep a sheet for sure, save it as a file.

Limits. Only A4 portrait, black on white. For 9 × 9 at most 4 sudokus fit on a sheet, otherwise the squares would be too small to write in. The heading is set in Helvetica: characters this font does not know (emoji, some letters of other languages) are dropped and named at the field. For 4 × 4 with symmetric clues there are only about 12,000 different puzzles: none appears twice on one sheet, but one can repeat across many sheets. Without symmetry this is much rarer. Very rarely the tool finds no puzzle for a No. that needs exactly the chosen level; then the easier level is shown at the sudoku and the preview says so.

Nothing is saved. The page remembers neither settings nor puzzles. The file from “Save as file” contains the settings, the numbers and the given symbols, no solutions; the tool works those out again when loading.