🧩 This logic grid puzzle is interactive right here on the page — click a cell to cycle it blank → ✓ → ✗ → blank as you work through the clues. Prefer paper? It also prints on a single page as a blank grid to fill in by hand, with a fold-over answer key at the bottom. Suitable for ages 10+ — no special knowledge needed, just careful deduction.
Five students each entered a different project in the school science fair. Use the clues to work out who built what — mark ✓ for true and ✗ for false as you go.
Chemistry
Astronomy
Robotics
Botany
Geology
Dara
Iris
Finn
Sasha
Nolan
Clues
Dara did not build the astronomy project.
Dara did not build the robotics project.
Dara did not build the botany project.
Iris did not build the robotics project.
Iris did not build the botany project.
Dara did not build the geology project.
Iris did not build the geology project.
Finn did not build the botany project.
Finn did not build the geology project.
Sasha did not build the geology project.
✂ fold backward along this line to hide the solution ✂
Solution hidden on screen — it prints automatically.
Solution
Chem
Astr
Robo
Bota
Geol
Dara
✓
Iris
✓
Finn
✓
Sasha
✓
Nolan
✓
How to Solve This Logic Grid Puzzle
Every clue here rules something out rather than telling you the answer directly — that's normal for logic grid puzzles, and it's exactly what the grid is for.
Find the row with the most crossed-off cells first. Dara has four different projects ruled out across clues 1, 2, 3, and 6 — that only leaves one blank cell in her row, so it must be a ✓. Once Dara is placed, cross her project off for everyone else.
Combine a row's clues with what you've already placed. Iris has three projects ruled out directly (clues 4, 5, and 7). With Dara's project now crossed off too, only one option remains open for Iris.
Keep the chain going. Finn has two projects ruled out directly (clues 8 and 9); once Dara's and Iris's projects are also crossed off his row, only one cell is left. The same happens for Sasha with a single direct clue (10) plus everything already placed — and Nolan's project falls out by pure elimination, with no clue naming him at all.
Every clue here is a "not" statement — nothing is handed to you directly, and with five items instead of four you'll need to stack several negative clues on the same row before a cell locks in. That's what makes a 5×5 grid a genuine step up: each solved row unlocks the next, but you have to find the right row to start with. For the full method, see our complete logic puzzle solving guide.
About This Puzzle
The Science Fair is a 5×5 grid, built the same way as The Talent Show: each row has one fewer clue than the last, so the puzzle solves itself in a clean cascade — Dara first, then Iris, then Finn, then Sasha, until Nolan's project falls out by elimination alone. All ten clues are "not" statements, and each one is necessary — take any single clue away and more than one solution becomes possible.