Maths Mission: The Amazing Number Detective

Materials Needed

• 10–20 small objects, such as blocks, coins, buttons, or toy pieces
• Paper and pencil
• A timer
• Three small cards or pieces of paper labeled Odd, Even, and Not Sure

Learning Objectives

By the end of the lesson, the learner will be able to:

• Explain that an even number can be split into equal pairs with none left over.
• Explain that an odd number has one left over when objects are put into pairs.
• Sort numbers as odd or even and explain how they know.

Success Criteria

Success looks like:

• Making equal pairs correctly.
• Using the words odd, even, pair, and left over.
• Correctly sorting at least 8 out of 10 numbers.
• Explaining the answer, not just guessing.

Introduction: The Number Detective Challenge — 2 Minutes

Hook: “A number detective has found a secret clue! Some numbers like to stand in pairs, but other numbers always leave one number alone. Can you discover which numbers are which?”

Tell the learner:

“Today you will investigate numbers. You will learn how to tell whether a number is odd or even by making pairs.”

Ask:

• “What does it mean when two things are a pair?”
• “Can you think of a number of shoes? Are shoes usually odd or even?”

Body: Investigate, Practice, and Play — 11 Minutes

1. I Do: Watch the Teacher or Adult Model — 3 Minutes

Place 6 objects in a row. Move them into pairs.

Say:

“I can make 3 pairs, and nothing is left over. That means 6 is even.”

Now place 7 objects in pairs.

Say:

“I can make 3 pairs, but 1 object is left over. That means 7 is odd.”

Write these examples:

• 6: 2 + 2 + 2 = 6, so 6 is even.
• 7: 2 + 2 + 2 + 1 = 7, so 7 is odd.

Quick check: Ask, “Is 4 odd or even? How do you know?”

2. We Do: Number Detective Race — 4 Minutes

Take turns choosing a number from 1 to 20. Use the objects to make pairs, or draw pairs on paper.

1. Choose a number.
2. Count out that many objects.
3. Put the objects into pairs.
4. Say, “The number is odd/even because…”

Use these numbers if needed: 3, 8, 11, 12, 15, 18.

Make it energetic: after each answer, the learner does:

• Two jumps for an even number.
• One spin for an odd number.

Think-pair-share option: The learner first thinks quietly, explains the answer to the adult or a toy, then shares the reasoning aloud.

3. You Do: Odd or Even Dash — 4 Minutes

Place the Odd and Even cards on opposite sides of the room. Call out one number at a time. The learner moves quickly to the correct card, then explains the answer.

Call out:

2, 5, 10, 13, 16, 19, 20, 9, 14, 17

For each number, ask:

“How can you prove it?”

If the learner is unsure, invite them to use the objects or draw pairs.

Conclusion: Mission Complete — 2 Minutes

Final Challenge

Ask the learner to choose one odd number and one even number between 1 and 20. They must show or explain how they know.

Recap

Say together:

“Even numbers make equal pairs with nothing left over. Odd numbers have one left over.”

Ask:

• “What makes a number even?”
• “What makes a number odd?”
• “Is 20 odd or even? Prove it.”

Assessment

Formative Assessment

• Watch whether the learner makes correct pairs.
• Listen for the words “pair” and “left over.”
• Ask the learner to explain answers during the race.

Summative Assessment

Give the learner these five numbers: 4, 7, 12, 15, 18. The learner sorts them into odd and even groups and explains at least four answers correctly.

Differentiation and Choice

• Support: Use numbers from 1 to 10 and allow the learner to build every number with objects.
• Extra support: Point out that numbers ending in 0, 2, 4, 6, or 8 are usually even.
• Extension: Ask, “Can you find all the even numbers between 1 and 20?” Then ask, “What pattern do you notice?”
• Creative choice: The learner can invent a number-detective riddle, such as, “I am between 10 and 15. I am odd. What numbers could I be?”
• Quiet alternative: Replace the movement race with sorting number cards or writing odd and even numbers in two columns.