Number Detectives: The Case of the Missing Toy

Materials Needed

• 10 small toys, blocks, or counters
• Number cards labeled 0–5
• Paper and crayons
• A small box or bag
• Optional: a tablet or computer for typing pretend “number code”

Learning Objectives

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

• Count objects from 0 to 5.
• Show that taking one object away from one object leaves zero objects.
• Match a group of objects with the correct number card.
• Use words such as more, less, none, and zero.
• Create and explain a simple number story.

Success Criteria

The child is successful when they can:

• Count a group of up to five objects accurately.
• Act out “one take away one” using toys.
• Choose the number card that shows how many objects are left.
• Explain that zero means none.

Introduction: The Number Mystery

Time: 5 minutes

Place one toy in the box and say:

“Oh no! A tiny number detective needs help. There is one toy in the box. What happens if the toy comes out?”

Let the child take the toy out. Ask:

• “How many toys were in the box?”
• “How many toys are in the box now?”
• “Are there any toys left?”

Say: “When there are no toys left, we say there are zero toys. Zero means none.”

Tell the child: “Today we will be number detectives. We will count, take away, and make number stories.”

Body: Learn and Practice

I Do: Teacher or Adult Demonstration

Time: 5 minutes

1. Put one block on the table.
2. Touch it and count: “One.”
3. Move it away and say: “One block take away one block leaves zero blocks.”
4. Place the number cards 1 and 0 beside the blocks at the correct times.

Use simple hand motions:

• Hold up one finger for one.
• Move the finger away for take away.
• Show empty hands for zero.

Quick Check: Ask, “If I have one teddy and put it away, how many teddy bears are on the table?”

We Do: Number Detective Games

Time: 8 minutes

Game 1: Count the Toys

1. Place 1–5 toys in front of the child.
2. Invite the child to touch each toy while counting.
3. Ask the child to find the matching number card.
4. Mix up the toys and repeat with a different amount.

Say: “Let’s check together. Touch each toy one time. What number tells how many toys there are?”

Game 2: Take One Away

1. Place two toys on the table.
2. Ask the child to count them.
3. Have the child move one toy into the box.
4. Ask how many toys are left on the table.
5. Repeat with one toy so the answer becomes zero.

Use playful language: “The toy is going on a little trip. How many toys are still here?”

Think, Pair, and Tell

If another person is available, the child tells that person the answer. If working one-on-one, the adult can pretend to be a friendly teddy bear who needs help.

Ask:

• “What does zero mean?”
• “Which group has more toys?”
• “Which group has fewer toys?”
• “Can you make a group with no toys?”

You Do: Make a Number Story

Time: 7 minutes

Invite the child to choose a toy and create a short story. Offer these choices:

• A toy picnic
• A toy train ride
• A toy animal snack
• A toy clean-up game

Help the child make a story such as:

“One bear had one cracker. The bear ate the cracker. Now the bear has zero crackers.”

Ask the child to:

1. Choose one toy.
2. Count one object beside it.
3. Move the object away or put it in the box.
4. Show the number card for zero.
5. Draw the story on paper.

Encourage creativity: “Your story can be funny. Maybe a dinosaur eats the last cookie!”

Optional Pretend Code Connection

Time: 3 minutes

Explain: “Computers use special number words and symbols. We can make our own safe pretend code.”

Write or say:

1 take away 1 = 0

Have the child act out each part with toys:

• 1: Put one toy down.
• Take away: Move it away.
• 1: Show that one toy was moved.
• 0: Show the empty space.

Remind the child: “Our pretend code tells a number story. It means one toy goes away, and none are left.”

Formative Assessment

Check understanding during the lesson by asking the child to:

• Count a group of three toys.
• Find the number card for three.
• Take one toy away from a group of two.
• Show how many toys are left.
• Make a group of zero toys.

Give specific feedback:

• “You touched each toy once. That helped you count carefully.”
• “You noticed the table was empty. Empty means zero.”
• “You chose the number card that matches your toys.”

Summative Assessment: Number Detective Challenge

Give the child three challenges:

1. Make a group of four toys and count them.
2. Take one toy away and tell how many remain.
3. Make one toy group, take the toy away, and show zero.

The child meets the objective if they complete at least two challenges with little or no help and can explain that zero means none.

Differentiation

Support for a Child Who Needs More Help

• Use only one or two toys at a time.
• Count slowly while touching each object.
• Use hand motions and an empty bowl to show zero.
• Offer two number cards to choose from.
• Repeat the same story several times with different toys.

Extension for a Child Ready for More

• Practice taking one away from groups of up to five.
• Compare two groups and identify which has more or fewer.
• Invent a new number story using drawings.
• Arrange number cards in order from 0 to 5.
• Ask: “What could we add to zero to make one?”

Conclusion: Tell What We Learned

Time: 3 minutes

Invite the child to finish these sentences:

• “Today I counted…”
• “Zero means…”
• “When I take one toy away from one toy, I have…”

Review together:

“Today we counted toys, moved one toy away, and learned that zero means none. We also made a number story using one take away one equals zero.”

End with a playful chant:

“One toy here, one toy gone—zero toys are left at dawn!”

Optional Follow-Up Activities

• Look for groups of zero, one, two, three, four, and five items around the home.
• During snack time, count crackers and notice what happens when the last one is eaten.
• Draw a picture showing one balloon popping and zero balloons remaining.
• Play “What’s Missing?” by hiding one object and asking how many are left.