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📈 LVL 1
🪙 0
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Case #404: The Missing Number
5 + ? = 12
Identify the Missing Number

Detective Dog

Crack the Case of the Missing Number!

There's a mystery in the math lab! Detective Dog needs a sharp-eyed partner to solve algebraic puzzles. This game introduces children to missing number problems in a fun, noir-themed setting.

Targeting Year 1 and 2, this game moves beyond simple calculation (e.g., 5 + 3 = ?) to algebraic concepts (e.g., 5 + ? = 8), helping children understand the equals sign as a balance.

🕵️‍♂️ The Investigation

  • 🔍
    Examine the Evidence Look at the equation on the board. One number has been stolen and replaced by a red question mark!
  • ⚖️
    Weigh the Facts Remember that the equals sign (=) means "the same as". The left side must equal the right side.
    Example: If 5 + ? = 12, what do you add to 5 to get 12?
  • 🔦
    Identify the Suspect Pick the correct number from the lineup to solve the case and earn your detective badge.

📚 Curriculum Focus (Algebra)

Detective Dog builds the foundations of algebra:

  • Missing Numbers Solve one-step problems that involve addition and subtraction, using concrete objects and pictorial representations, and missing number problems.
  • Inverse Operations Use subtraction to check addition (e.g., solving 5 + ? = 12 by doing 12 - 5).
  • Equality Understand the equals sign. Most children think it means "the answer is". This game teaches it means "balance".

🧠 Algebraic Thinking

Many high school students struggle with algebra because they were never taught to see the structure of a number sentence.

By playing "Find the Missing Number" early even with simple numbers, children develop flexibility in their thinking. They stop just "crunching numbers" and start reasoning about them.

👨‍👩‍👧 Detective Training

The Hiding Box:

  • Put 10 items (grapes, lego bricks) in a bowl.
  • Take some out and hide them under a cup. Leave 6 visible.
  • "We had 10. Now we can see 6. How many are under the cup?"

Case File Closed. Good work, Detective.