Bulls & Cows is a classic number-deduction game (a predecessor to Mastermind). Students use feedback — bulls (right digit, right place) and cows (right digit, wrong place) — to infer a secret 4-digit code. It’s a natural fit for reasoning, patterns, and efficient search.
Curriculum Links
- Logical reasoning and argumentation
- Number sense and place value
- Combinatorics and search strategies
- Data interpretation (using feedback to guide choices)
Classroom Setup Options
Warm-up (5–10 mins): One code on the board; students propose guesses; the class computes bulls/cows together.
Small-group stations: Teams race to solve the daily code, recording attempts and strategies.
Homework: Use Unlimited mode for practice without time pressure.
Competition: Track streaks or time-to-solve; discuss which strategies were most efficient and why.
How to Play (Quick)
- Enter a 4-digit guess with no repeated digits (unless a mode allows repeats).
- Read the feedback: Bulls (right digit, right place) and Cows (right digit, wrong place).
- Eliminate impossibilities and refine your next guess.
- Reach 4 Bulls to win.
Effective Solving Strategies
- Cover more ground early: Start with four distinct digits (e.g., 1 2 3 4) to maximise information.
- Eliminate digits fast: A 0-Bull/0-Cow result removes those digits entirely.
- Localise positions: With 2 Cows, rotate those digits to test positions systematically.
- Control variables: Near the end, change only one or two digits per guess so feedback is clear.
- Record attempts: Keep a simple grid of digits/positions; the attempts table in the UI helps.
- In Bull Rush: Use all five clues together — they’re designed to narrow to a single consistent code.
Teach with Pencil & Paper
Bulls & Cows works beautifully as an unplugged classroom activity — no devices required. Students can work in pairs or small groups to practise logic and deduction.
- Choose a secret number: One student writes a 4-digit number with all unique digits (no repeats).
- Make a guess: The other student writes a guess — also 4 unique digits.
- Give feedback: The “host” counts Bulls (right digit, right place) and Cows (right digit, wrong place) and tells the guesser.
- Refine and repeat: Students keep guessing, using feedback to eliminate possibilities, until they reach 4 Bulls.
Tip: Provide a simple tracking grid so students can mark which digits/positions are still possible.
Generate Custom Puzzles with Haystack
Haystack lets you create your own Bulls & Cows-style challenges in seconds — perfect for tailored practice, extension work, or quick bell-ringers.
- Pick a difficulty: Choose from Easy, Medium, or Hard. Each setting balances digits and number of given clues to tune the challenge.
- One-click share: Each generated puzzle has a unique link you can paste into your LMS, slide deck, or email.
- Play or print: Students can solve online (with keypad and attempts table) or you can print the generated clue set for a no-tech activity.
- Classroom ideas: Assign different groups different difficulties; compare strategies; have students design “fair” puzzles and swap.
Suggestion: Start the class with an Easy puzzle for confidence, then move to Medium or Hard for deeper reasoning.
Under the Hood: How Bull Rush Builds a Unique Daily Puzzle
Bull Rush ensures every learner sees the same daily challenge and, with careful reasoning, can deduce one unique answer:
- Daily seed: The date acts like a recipe — it produces the same 4-digit secret (no repeated digits) for everyone that day.
- Clue creation: The game tests sets of five example guesses and keeps them only if those five lines, taken together, leave exactly one possible solution in the whole search space.
- Uniqueness check: If more than one code fits, the set is rejected and a new set is tried — until there’s a single provable solution.
- Persistence: A small local record lets students revisit that day’s puzzle and see the same clues and result.
Classroom win: two different classes (or home and school) can discuss the same logical puzzle and compare strategies.
History (Short)
The pen-and-paper game dates back decades, with variants worldwide. Its commercial cousin Mastermind popularised the core mechanic in the 1970s. Our web version adds helpful modes: the Daily challenge, Bull Rush, Unlimited practice, and Multiplayer duels.
Connect & Motivate
Encourage sharing results (emoji grids) and checking the global leaderboard to see how they compare with players around the world.