What It Actually Trains
It is worth being precise, because “logical reasoning” says nothing. One of these cases asks for four specific things, and it asks for all of them at once.
Deducing by elimination. You do not make progress by finding where someone is, but by ruling out where they cannot be. It is the hardest step to teach, and here it gets practiced on every move: each person placed crosses out an entire row and an entire column.
Reading precisely. Every word on a card counts. “Next to” means on the neighboring square and in the same area: two squares that touch but have a wall between them do not count. Anyone who skims gets it wrong, and finds out on their own.
Justifying. This is the good one. The question that turns the activity into a lesson is not “Who did it?” but “How do you know they were there?” Because the solution is unique and forced, there is always an answer and it can always be checked. Opinions do not count.
Finding your way around a map. Rows, columns, above, to the left, inside and outside an area. It gets practiced without ever being named.
What Age It Works From
The only real requirement is being able to read a short sentence and understand it. No sudoku experience, no times tables, no logic puzzles before.
With the small maps and few suspects, it works in elementary school: they take a few minutes and the step-by-step fits on a whiteboard. The big maps, with more people and clues that refer to each other, are for middle school and up… and for the teachers' puzzle club, which is usually where the fiercest arguments happen.
For the youngest, there's a logic puzzle for kids with three pets and two clues, to warm up before a case.
At libraries and nursing homes, the same thing happens with the ages swapped: a small case fits nicely on a table and gets solved together, talking it through out loud.
A Half-Hour Session, Step by Step
What follows is designed for a one-off class, with no prep and no screens.
Five minutes of rules. There are four, and they are better taught by solving a tiny case in front of everyone than by explaining them: one person per row and per column; the cards tell the truth; nobody can be on a square with furniture; whoever ends up in the victim's area is the murderer.
Fifteen minutes on the case, in pairs. Pairs work better than solo: it forces students to say out loud why they are crossing out a square, which is exactly what you want to hear. One pencil and one eraser per pair.
Five minutes of sharing. Before giving the solution, have someone explain the first step: which card they tackled first and why that one. That is where you see who understood the method and who got lucky.
Five minutes of solution. The solution PDF comes with the reasoning written alongside, not just the finished map: read it out loud and compare it with what each pair did.
Handling Students Who Work at a Different Pace
The trick is not to change the topic but the size. The same setting comes in several levels: whoever finishes early does not sit staring at the ceiling, they take the big case from the same setting and keep going with the same rules.
And since the solution comes as a separate PDF, you can hand it out at the end or leave it on a table at the back for anyone who wants to check their own work. That takes care of half the raised hands.
If someone is completely stuck, the answer is not to tell them the murderer: ask them which of the cards in front of them is the most specific. Almost always, they have not looked at it.
The Material, Free and With Written Permission
Under printable cases there are cases ready to photocopy, free and with no sign-up. Each one comes as three files: in color, in black and white — the one that actually gets printed, because it goes easy on the ink — and the solution as a separate PDF, to hand out when the time comes and not before.
And the permission, which is what you need to bring it into a classroom: free to print and hand out in classrooms, libraries and nursing homes. All we ask is that you keep the credit: sudokudetective.com. It is written on the download page itself, so you can show it to anyone who asks.
They are available in all seven languages of the site, which also makes them useful for a language class: the same case in two languages, with the vocabulary of the house and of positions.
Three Details That Head Off Half the Questions
Explain “next to” before you start, and draw it. It is the only rule people misread, and once you have explained it, nobody asks again.
Insist on crossing out in pencil. Students who do not mark their ✕s try to keep it all in their heads, get stuck and give up. Those who cross out keep moving.
Do not hand out the solution with the case. It sounds obvious, but it is not: if it is on the desk, it gets looked at. Better at the back of the room, or at the end.
Alice“I was next to the plant.”
Living RoomKitchenHallwayAnd If the Group Gets Hooked: The Book
When a case works in class, someone always asks where to find more. The long answer is Sudoku Detective: a paperback, in full color, with illustrated settings and the solution to every case explained step by step. It belongs in a classroom library and makes a good end-of-year gift; the cases in the book are only in the book, not on the website.
The short, free answer: you can play in the browser, with no account and nothing to install, and new cases every week, and here are the full rules with a case solved from start to finish, in case you want to read them before the session.
Frequently Asked Questions
Can I photocopy the cases for my students?
Yes. They are free to print and hand out in classrooms, libraries and nursing homes. All we ask is that you keep the credit: sudokudetective.com
Do I need computers or tablets?
No. The printable cases are solved on paper, in pencil. If you would rather project one, the website runs in the browser with nothing to install.
How long does a case take?
A small case takes a few minutes; a big one can take a good half hour or more. For a one-off session, the easy approach is one small case per pair and a harder one in reserve.
Do you need to know how to play sudoku?
No. Only one rule comes from sudoku: one person per row and one per column. The rest is deducing from what the cards say, and it takes five minutes to explain.
Does it work at a library or a nursing home?
Yes, and that is where the tabletop format works best: one case, two or three people, and talking it through out loud. The license expressly covers that use.
What languages are they in?
All seven languages of the site: Spanish, English, French, Italian, German, Portuguese and Dutch. The same case in two languages makes a foreign-language activity.
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