Small Sudoku puzzles for children and complete beginners: a 4×4 grid with the digits 1 to 4, and a 6×6 grid with the digits 1 to 6. Same rule as the full-size game, few enough squares to finish in a couple of minutes. Free, nothing to install, and no sign-up.
Sixteen squares and the digits 1 to 4. Half the squares are filled in already, and the boxes are the four 2×2 corners.
Every row, every column and every outlined box has to contain each digit once — and only once. That is the whole game, at every size. On the 4×4 board the digits are 1, 2, 3 and 4; on the 6×6 board they go up to 6; on the full-size 9×9 board they go up to 9. Nothing else changes, which is exactly why a small grid is a fair way to learn: a child who can finish a 4×4 already knows how Sudoku works.
There is no adding up and no counting. The digits are just four, six or nine different symbols that are not allowed to repeat. Some teachers hand out the same puzzles with coloured shapes instead of numbers for exactly that reason — the reasoning is identical.
Sixteen squares, four rows, four columns, and four boxes of 2×2 in the corners. Eight squares are filled in to start with, so there is always a move available and the whole puzzle takes a minute or two.
The way in is to find a row, column or box that already has three of its four digits. Whatever is missing goes in the empty square — there is nowhere else for it to go, and nothing else can go there. Each digit placed usually completes something else, so a 4×4 tends to fall over in a chain once the first square goes in.
When that runs out, pick a digit and look for it. Say a box has no 3 in it yet and two empty squares. If one of those two squares is in a row that already has a 3 further along, the 3 cannot go there — so it goes in the other one. That single move is cross-hatching, and it is the technique that carries an adult through most of a 9×9 puzzle too. A 4×4 grid is the easiest place in the world to see it working.
Thirty-six squares, the digits 1 to 6, and the first genuinely interesting change: the boxes are not square. A 6×6 grid is divided into six boxes that are two rows tall and three columns wide, because that is the only way to cut a 6×6 grid into six equal boxes of six squares.
That is worth pointing out to a child rather than letting them discover it as confusion. The box is still "a group of six squares that needs all six digits" — it just is not the shape they expect. Once that lands, the 6×6 plays like a slower 4×4, and it is the right bridge to the full-size grid.
Sixteen of the thirty-six squares start filled. Every puzzle here can be finished by looking, without pencil marks and without guessing.
A few things that make the difference between a puzzle a child finishes and one they walk away from:
Sudoku is genuinely good practice at the thing it looks like it is practising: holding a few constraints in mind at once and working out what they force. It is not a maths exercise, and a child who dislikes arithmetic may well like this.
Earlier than most people expect, because the barrier is not arithmetic — it is whether a child can recognise four different symbols and hold "this one is already used" in mind while they look somewhere else. Children who can do a shape-matching puzzle can usually do a 4×4 grid with someone sitting next to them, and can usually do one alone a while after that.
The honest answer is that it varies enormously and the grid will tell you faster than any guideline will. Put a 4×4 in front of them. If the first square takes a long time but arrives with a reason attached, they are ready and just slow, which is fine. If the squares are being filled at random, come back in a few months — nothing is lost, and pushing through it is how a child decides that puzzles are a chore.
For a child who is reading fluently and counting comfortably, the 6×6 board is usually a better starting point than the 4×4, which can feel babyish once it is understood. There is no order you have to go in: both boards are on this page, and switching between them costs a tap.
When the 6×6 board is being finished without help and without long pauses. The full-size grid is not harder in kind — it is the same rule with more squares to scan, and the scanning is what has already been learned here.
The step up to try is easy 9×9 Sudoku, which starts with about 42 of its 81 squares filled and can be solved by scanning alone, exactly like the boards on this page. If the rules need restating for a grown-up joining in, how to play Sudoku covers them in about five minutes.
For the classroom, the kitchen table, or a car journey, the printable Sudoku sheets will print 4×4 and 6×6 grids too — up to six to a page, with an answer sheet if you want one. Every puzzle here and there is made fresh when you ask for it and checked to have exactly one solution, so a child can never hit a grid that does not work out.