Cross It Out! Reading “Not” Clues in Logic Puzzles
- Grade band
- 2
- Duration
- 30 minutes
- Skill
- Using negative clues to eliminate possibilities
- Standards
- RI.2.1 — Ask and answer such questions as who, what, where, when, why, and how to demonstrate understanding of key details in a text.
- MP.1 — Make sense of problems and persevere in solving them.
- Materials
- Student worksheet (printable, included)
- Clue sort cards (printable, included)
- Pencils
Learning objectives
- Students will be able to classify a clue as one that gives a ✓ (a match) or one that gives an ✗ (a “not” clue).
- Students will be able to apply several “not” clues to eliminate possibilities and identify the one answer that is left.
- Students will be able to answer “who” and “how do you know” questions about a puzzle by pointing to the clue that proves it.
Lesson procedure
- Warm-up (4 minutes) — I Do. Say: “I'm thinking of a color in our classroom flag. It's not red. It's not white.” Let students guess. Point out that you never said the answer — you just crossed things out until only one was left.
- Two kinds of clues (6 minutes) — I Do / We Do. Write two clues on the board: “Leo has the red kite.” and “Maya's kite is not red.” Ask: “Which one tells us a match? Which one only crosses something out?” Label them ✓ clue and ✗ clue. Then sort the clue cards (Part 3) as a class, or use the smartboard sort below.
- Kite puzzle together (8 minutes) — We Do. Read the three kite clues one at a time. After each one, students put an ✗ on their own grid. After Clue 2, ask: “Maya has only one box left without an ✗. What does that mean?” (It must be her kite — mark ✓.) Finish the grid together.
- Sports puzzle on your own (8 minutes) — You Do. Students solve Part 2 independently, then answer the two “How do you know?” questions by writing the clue number that proves each answer.
- Turn and talk (4 minutes) — Closure. Partners explain to each other: “How can a puzzle with only ✗ clues still have an answer?” Share one or two explanations with the class.
Printable worksheet
Part 1: The kite puzzle. Each kid has one kite. Read each clue. Put an ✗ in a box when a clue says NOT. When a kid has only one empty box left, put a ✓ there.
- Maya's kite is not red.
- Maya's kite is not blue.
- Leo's kite is not blue.
| 🟥red | 🟦blue | 🟩green | |
|---|---|---|---|
| Maya | |||
| Leo | |||
| Zoe |
Maya's kite is . Leo's kite is . Zoe's kite is .
Part 2: The sports puzzle. Each kid plays one sport. Solve it on your own.
- Owen does not play soccer.
- Priya does not play soccer.
- Priya does not swim.
| ⚽soccer | 🏊swimming | 🎾tennis | |
|---|---|---|---|
| Owen | |||
| Priya | |||
| Sam |
1. Who plays soccer? How do you know? Clues #
2. What does Priya play? How do you know? Clues #
Part 3: Clue sort cards. Cut apart the cards. Sort them into two piles: ✓ clues (tell you a match) and ✗ clues (cross something out).
Try it on your smartboard
The same clue sort, on screen. Drag each clue to the kind of mark it gives you — works with touch, a stylus, or a mouse.
✓ Gives a match
✗ Crosses one out
Background for the teacher
Logic puzzles are built mostly from negative information. A clue like “Maya's kite is not red” doesn't tell you the answer — it removes one possibility. Students who expect every clue to hand them a match often stall on puzzles like these. The skill this lesson builds is trusting elimination: when every option but one is crossed out, the last one is proven, even though no clue named it.
Watch the wording on the sort cards. “Never,” “isn't,” and “does not” are all ✗ clues, and so is “The dog is not Ana's,” where the person and the thing are flipped around. Seeing the same idea phrased several ways helps students read for meaning instead of hunting for the word “not.” Asking “How do you know?” and having students point to clue numbers is the logic-puzzle version of citing the text — it turns a guess into an answer they can defend.
Differentiation
Support: Before marking the grid, have students restate each clue in their own words starting with “So…” (“So Maya doesn't have red”). Give them the Part 1 grid with the first ✗ already drawn.
Extension: Challenge students to rewrite the kite puzzle using only two clues that still lead to exactly one answer — then test whether a partner can solve it.
ELL support: Show the negative words students will see (not, never, doesn't, isn't) on an anchor chart with a ✗ beside each. Use real colored objects for the kite puzzle so color words are supported visually.
IEP/504 support: Reduce the clue sort to four cards (two of each kind), and let students answer the “How do you know?” questions orally or by pointing to the clue on the page instead of writing.
Answer key (for teachers)
Part 1 — Kites. Maya: green · Leo: red · Zoe: blue. (Clues 1 and 2 leave Maya only green. Clue 3 plus green being taken leaves Leo red. Zoe gets blue.)
Part 2 — Sports. Owen: swimming · Priya: tennis · Sam: soccer.
1. Sam plays soccer — Clues 1 and 2 (Owen and Priya don't, so Sam must).
2. Priya plays tennis — Clues 2 and 3 (not soccer, not swimming).
Part 3 — Clue sort. ✓ clues: Leo has the red kite; Sam plays soccer; The cat belongs to Ben; Maya flies the green kite. ✗ clues: Zoe's kite is not green; Owen does not play tennis; The dog is not Ana's; Priya never swims.
Digital extension (optional)
For more practice reading clues, try a case in Sleuth Scouts. Kids tap grid boxes to mark ✓ and ✗ as they read each clue — a good next step once they're comfortable crossing things out on paper.