Free Teacher Resources

Sudoku

Name: ______________________
8
7
6
4
7
9
1
2
5
8
3
4
1
8
2
1
7
6
9
5
3
5
7
5
6
4
7
6
9
8
8
4
Free printable resources at freeteacherresources.org

About the Sudoku Generator

Each puzzle here is generated from a complete, valid solution and then has cells removed one at a time, checking after every removal that the puzzle still has only one possible answer. That's the difference between a real sudoku and a grid of randomly blanked-out numbers: there's exactly one way to finish it.

Difficulty is controlled by how many starting numbers stay on the board — a beginner puzzle gives away forty clues, while a hard one leaves twenty-six and a lot more deduction.

How to use it in your classroom

  1. Choose a difficulty: Easy, Medium, or Hard.
  2. Preview the puzzle, then print, or click shuffle for a different puzzle at the same difficulty.
  3. Turn on the answer key when you need a completed grid for grading or for your own reference while students work.

Tips from the classroom

  • Easy puzzles are a reasonable entry point for upper-elementary students who already understand rows, columns, and the 3×3 boxes; Hard suits older students or a genuine free-time challenge.
  • Print a few puzzles at once for an early-finishers folder — since each is freshly generated, no two are the same even at matching difficulty.
  • Keep one answer-key copy per difficulty level so you're not regenerating a solution from scratch every time a student wants to check their work.
  • Sudoku makes a clean sub-day activity: the rules take one sentence to explain, and there's no setup beyond printing it.

Frequently asked questions

Is it possible for a puzzle to have more than one solution?

No. The generator checks the solution count while removing cells and stops removing a cell if doing so would create a second valid solution.

What's the actual difference between Easy, Medium, and Hard?

It's the number of starting clues left on the board: forty for Easy, thirty-two for Medium, twenty-six for Hard. Fewer clues means more steps of deduction before numbers are confirmed.

Can I get the same puzzle again later?

Not directly. Each shuffle generates a new random puzzle, so if you want to reuse one, save the PDF or printed copy.