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Brain teasers
Ten puzzles, each one running on a piece of mathematics you can name. Not maths dressed up as a game — a game that turns out to be maths once you notice what you are doing.
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Bank shot
Aim off the cushions to sink the ball. No luck, just angles.
Reflection: angle in equals angle out
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Sudoku
Every row, column and box holds 1 to 9 exactly once.
Constraint deduction
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Lights out
Every press flips a light and its neighbours. Turn them all off.
Parity and arithmetic mod 2
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Tower of Hanoi
Move the stack across. Never put a bigger disc on a smaller one.
Recursion, and why 2ⁿ − 1 grows so fast
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Nonogram
Numbers along each edge say how the filled runs are grouped.
Deduction from run-length clues
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Fifteen
Slide the tiles back into order using the one empty square.
Permutation parity
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Map colour
Colour every region so no two touching regions match.
Graph colouring and the four-colour theorem
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Bridges
Join the islands so each one has exactly its number of bridges.
Vertex degree in a graph
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Takuzu
Fill the grid with 0s and 1s. Never three in a row.
Binary logic and counting constraints
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Area maze
Find the missing length using only whole-number areas.
Area arithmetic without algebra
What these are for
Every puzzle here is generated fresh in your browser, so you never run out and no two people get the same one unless they use the same puzzle number. Nothing is timed, nothing is scored, and nothing is sent anywhere. If you want the part of this site that actually tracks what a student has learned, that is the classroom.