Deduce #70: The science fair — the solution

The Deduce puzzle from October 23, 2026, worked through clue by clue: 8 clues, 4 rounds of crossing off, and no guessing anywhere.

The puzzle

Four people — Vince, Paige, Benji and Luis — and three things to work out about each: their project, school and grade. The clues only ever rule things out.

1. The one from Monroe School is exactly 2 grades after Luis.
2. The one from Madison School is in a lower grade than the one who made the ant farm.
3. Benji is in a lower grade than the one from Madison School.
4. Vince is not the one from Madison School.
5. Benji is the one who made the catapult.
6. Paige is the one in 6th grade.
7. The one from Garfield School is in a lower grade than the one who made the rocket.
8. Vince is the one who made the rocket.

The walkthrough

A round is one pass over the clues. Each round applies what the last one settled; every step below is an elimination the clues force, in the order a solver would take them.

Round 1

Start with every possibility open, and take the clues in order.

Clue 1, “The one from Monroe School is exactly 2 grades after Luis”: Monroe comes off Luis; 5th and 6th come off Luis.

Clue 3, “Benji is in a lower grade than the one from Madison School”: Madison comes off Benji; 6th comes off Benji.

Clue 4, “Vince is not the one from Madison School”: Madison comes off Vince.

Clue 5, “Benji is the one who made the catapult”: catapult comes off Vince, Paige and Luis. That settles it: Benji’s project is catapult.

Clue 6, “Paige is the one in 6th grade”: 6th comes off Vince. That settles it: Paige is in 6th grade.

Clue 7, “The one from Garfield School is in a lower grade than the one who made the rocket”: Garfield comes off Paige.

Clue 8, “Vince is the one who made the rocket”: rocket comes off Paige and Luis. That settles it: Vince’s project is rocket.

Round 2

Go back over the clues with the new facts in hand.

Clue 2, “The one from Madison School is in a lower grade than the one who made the ant farm”: ant farm comes off Luis; Madison comes off Paige. That settles it: Luis’s project is crystals.

Clue 3, “Benji is in a lower grade than the one from Madison School”: 4th and 5th come off Benji; 3rd comes off Luis. That settles it: Benji is in 3rd grade and Luis is in 4th grade.

Clue 7, “The one from Garfield School is in a lower grade than the one who made the rocket”: Garfield comes off Vince; 3rd comes off Vince.

Round 3

Go back over the clues with the new facts in hand.

Crystals is Luis’s, so it comes off Paige. That settles it: Paige’s project is ant farm.

Nobody but Luis can still have Madison, so Luis’s school is Madison.

4th is Luis’s, so it comes off Vince. That settles it: Vince is in 5th grade.

Clue 1, “The one from Monroe School is exactly 2 grades after Luis”: Monroe comes off Vince and Benji. That settles it: Vince’s school is Franklin.

Round 4

Go back over the clues with the new facts in hand.

Franklin is Vince’s, so it comes off Paige and Benji. That settles it: Paige’s school is Monroe and Benji’s school is Garfield.

The answer

Previous: Deduce #69 (Thu, Oct 22) · Next: Deduce #71 (Sat, Oct 24) · All Deduce solutions

About Deduce

Deduce is Noggin’s daily logic grid: four people, three things to work out about each, and clues that never hand you an answer. Every puzzle has exactly one solution and can be finished by crossing off alone. How to play Deduce, or play today’s.