Everydoku4×4 and 6×6 sudoku
Faced with 50 empty cells on your first 9×9 board, it is hard to know where to look. Small boards shrink the same rule to something you can finish in minutes. They are a good start for adults new to sudoku and for children who have just learned their numbers.
4×4: getting the rule into your fingers
A 4×4 board uses only the digits 1 to 4, in four 2×2 boxes. Each row, column and box gets 1, 2, 3 and 4 once.
- Each cell touches only 7 others, so its row, column and box almost always narrow it to one digit. It is the perfect place to practise the naked single.
- Everydoku's 4×4 has one difficulty, Tutorial, with 1,000 boards. All of them can be finished with naked singles alone.
- A board takes a minute or two. Explain the rule, solve two or three together, and most people carry on by themselves.
6×6: a new box shape
A 6×6 board uses 1 to 6, and its boxes are 2 rows by 3 columns. Rectangular boxes feel odd at first; just follow the thick lines.
- Easy needs only naked singles. Normal also needs the hidden single.
- Normal boards are where you first learn to look at digits instead of cells. The habit of asking “where can 5 go in this box?” carries straight over to 9×9.
- A board takes about three to six minutes.
Solving with children
- Talk in pictures, not numbers. Start with “the same fruit can't appear twice in a row” and they quickly see that no arithmetic is involved. Digits are just different symbols.
- Start with lines that have one empty cell. If a row has 1, 2 and 3, the gap is 4. A few of those build confidence fast.
- Make mistakes safe. Everydoku shows a digit in red when it repeats in a row, column or box. Turn on “Show mistakes right away” in settings and it also flags digits that don't match the solution.
- Try paper too. The printable 4×4 and printable 6×6 pages print boards with their answers.
When to move up to 9×9
If you can finish several 6×6 Normal boards in a row without hints, you are ready for 9×9 Easy. 9×9 Easy boards need only naked singles, so the job is the same as 4×4 with more cells. After that, 9×9 Normal is where hidden singles really come in. The table on the guide's first page lists the techniques each level needs.