Math Detectives: The Mystery of Making 10
Materials Needed
- 10 small objects, such as buttons, blocks, coins, or toy animals
- Number cards from 0 to 10, or handwritten number cards
- Paper and pencil or crayons
- Two small bowls, cups, or paper plates
- Optional: dice, sticky notes, and a timer
Learning Objectives
By the end of the lesson, the learner will be able to:
- Find pairs of numbers that add up to 10.
- Use objects, drawings, and number sentences to show addition combinations.
- Explain how knowing number pairs helps solve addition problems quickly.
- Create and solve a simple “make 10” math puzzle.
Success Criteria
I can:
- Build two groups that make 10 altogether.
- Write an addition sentence, such as 6 + 4 = 10.
- Find at least eight different ways to make 10.
- Explain how I know my answer is correct.
Introduction: The Number Detective Mystery
Hook: Tell the learner: “A secret number has 10 friends. Each friend comes in a pair, and the two numbers always add up to 10. Can you become a number detective and discover all the pairs?”
Show 10 objects. Ask:
- “What do you notice about these objects?”
- “If I hide some objects, how could you figure out how many are hidden?”
- “What number goes with 3 to make 10?”
Explain that today’s goal is to discover the different number pairs that make 10. These pairs are called number bonds. A number bond shows how numbers fit together to make a total.
Body: Explore, Practice, and Apply
Part 1: I Do — Teacher or Adult Demonstration
Place 10 objects in a row. Move 1 object into one bowl and 9 objects into the other bowl.
Think aloud:
“I have 1 object in this bowl and 9 in the other bowl. When I put the groups together, I have 10. I can write 1 + 9 = 10.”
Repeat with another example, such as 4 and 6. Draw the two groups and write:
4 + 6 = 10
Point out that the order can change:
6 + 4 = 10
Ask the learner to explain why both equations have the same total.
Quick Check
Hold up 7 objects in one group and ask:
“How many more objects are needed to make 10?”
Look for the learner to answer 3 and explain using objects, fingers, a drawing, or counting forward.
Part 2: We Do — Number-Bond Hunt
Work together to find all the pairs that make 10.
- Write the numbers 0 through 10 on separate cards.
- Choose one card, such as 2.
- Ask, “What number belongs with 2 to make 10?”
- Use objects to check the answer.
- Write the matching equation: 2 + 8 = 10.
- Switch the order and write: 8 + 2 = 10.
Record the pairs together:
| First Number | Partner | Equation |
|---|---|---|
| 0 | 10 | 0 + 10 = 10 |
| 1 | 9 | 1 + 9 = 10 |
| 2 | 8 | 2 + 8 = 10 |
| 3 | 7 | 3 + 7 = 10 |
| 4 | 6 | 4 + 6 = 10 |
| 5 | 5 | 5 + 5 = 10 |
Ask the learner:
- “What pattern do you notice?”
- “What happens to one number when the other number gets larger?”
- “Why does the pair 5 and 5 work?”
Part 3: We Do — Shake and Split
Place 10 objects in a cup or container. Shake gently and pour the objects onto a table. Sort the objects into two groups based on where they land.
- Count the objects in each group.
- Say the number sentence aloud.
- Write or draw the equation.
- Repeat several times.
For example, if 6 objects land on one side and 4 land on the other, say:
“Six and four make ten. 6 + 4 = 10.”
Part 4: You Do — Number Detective Challenge
Invite the learner to solve these puzzles independently. The learner may use objects, drawings, fingers, or mental math.
- 3 + ____ = 10
- ____ + 7 = 10
- 5 + ____ = 10
- ____ + 1 = 10
- 8 + ____ = 10
After solving, ask the learner to choose two problems and explain how they found the missing number.
Part 5: Real-World Application — Snack Shop
Set up an imaginary snack shop with 10 pretend items, such as blocks representing apples, crackers, or cookies.
Give the learner a scenario:
“There are 10 snacks in the shop. A customer buys 6. How many snacks are left?”
Have the learner act out the problem by separating 6 items from the group of 10. Then write:
10 - 6 = 4 and connect it to the number bond 6 + 4 = 10.
Offer choices for additional scenarios:
- There are 10 toy animals. 3 are placed in a barn. How many are outside?
- There are 10 crayons. 8 are in a pencil box. How many are on the table?
- There are 10 building blocks. 5 are blue. How many are another color?
Part 6: Creative Task — Make a Number Puzzle
Ask the learner to create a puzzle for someone else to solve.
The puzzle must include:
- A drawing of 10 objects divided into two groups
- A missing number
- An addition sentence, such as ____ + 4 = 10
- An answer written on the back or hidden under a flap
The learner may decorate the puzzle as a treasure map, robot challenge, animal rescue, or space mission.
Formative Assessment
- Observe whether the learner accurately counts each group.
- Ask the learner to build a pair that makes 10.
- Present a missing-addend problem, such as 2 + ____ = 10.
- Ask the learner to explain an answer using objects, a drawing, or words.
- Listen for correct use of terms such as add, total, group, and number bond.
Summative Assessment: Show What You Know
Ask the learner to complete the following independently:
- Draw two groups that make 10.
- Write the matching addition sentence.
- Complete: 7 + ____ = 10.
- Complete: ____ + 3 = 10.
- Explain how knowing number bonds to 10 can help with a larger problem, such as 7 + 3 + 2.
Assessment Guide
- 4–5 correct: The learner has met the objective.
- 2–3 correct: The learner is developing the skill and should practice with objects or drawings.
- 0–1 correct: Review smaller number pairs first, then return to making 10.
Differentiation and Adaptations
Support for Learners Who Need More Help
- Use only pairs from 5 to 10 at first, such as 5 + 5, 4 + 6, and 3 + 7.
- Provide a ten-frame or a row of 10 spaces.
- Let the learner use counters, fingers, or a number line.
- Practice one pair at a time and repeat the language: “___ and ___ make 10.”
- Give two answer choices for each missing number.
Extension for Learners Ready for More
- Write both related addition equations for each pair.
- Connect addition and subtraction: 6 + 4 = 10, 10 - 6 = 4.
- Solve problems such as 8 + 2 + 5 by making 10 first.
- Create a story problem involving a number bond to 10.
- Time how quickly the learner can correctly identify number pairs, focusing on accuracy before speed.
Flexible Learning Options
- Hands-on: Use blocks, toys, snacks, or craft materials.
- Movement-based: Place number cards around the room and find matching partners.
- Digital: Use a virtual ten-frame or draw groups on a tablet.
- Verbal: Say number bonds aloud while an adult records them.
- Independent: Complete the number puzzle and assessment pages without assistance.
Conclusion: Detective Debrief
Ask the learner to complete these sentences:
- “Today I discovered that ____ and ____ make 10.”
- “I can check my answer by ____.”
- “Number bonds help me because ____.”
Review the key idea:
Numbers can be split into pairs that make a total of 10. Knowing these pairs helps us add and subtract more quickly.
Finish with a quick challenge: Say a number from 0 to 10 and have the learner respond with its partner. For example, say “9,” and the learner says “1.” Celebrate accurate thinking, clear explanations, and careful checking.