Fun with One Less: Understanding 1 − 1 = 0

Materials Needed

• Two small plates, bowls, or pieces of paper
• One small toy, block, pom-pom, or snack
• Number cards showing 0 and 1
• Paper and crayons
• A small box or bag
• Optional: a short children’s song about numbers

Learning Objectives

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

• Show that taking one item away from one item leaves zero items.
• Say and explain that 1 − 1 = 0.
• Use objects, drawings, or words to solve simple “take away” problems.
• Connect subtraction to everyday experiences, such as eating one snack or putting away one toy.

Success Criteria

The child is successful when they can:

• Start with one object.
• Take the object away.
• Show that nothing is left.
• Choose or say the number 0.
• Use the sentence: “One take away one is zero.”

Introduction: The Empty Plate Mystery

Time: 5 minutes

Place one toy or snack on a plate. Use an excited voice and say:

“Look! There is one snack on the plate. What do you think will happen if we take it away?”

Let the child make a prediction. Then take the item away and show the empty plate.

Say:

“The plate is empty! We had one. We took one away. Now we have zero.”

Tell the child:

“Today we will learn about taking one thing away. We will play, move, draw, and discover what zero means.”

Body of the Lesson

1. I Do: Teacher or Adult Demonstration

Time: 5 minutes

Place one block on a plate or piece of paper. Point to it and count:

“One.”

Write or show the number 1. Slowly move the block away and say:

“Take one away.”

Point to the empty plate and say:

“There are no blocks left. No blocks means zero.”

Show the number 0 and say:

“One take away one is zero. We write it like this: 1 − 1 = 0.”

Use simple gestures:

• Hold up one finger for 1.
• Move the finger down for “take away.”
• Show an empty hand for 0.

2. We Do: Take-Away Game

Time: 8 minutes

Invite the child to copy each step:

1. Put one object on the plate.
2. Count it together: “One.”
3. Ask, “Can you take one away?”
4. Have the child move the object into the box or bag.
5. Ask, “How many are left?”
6. Help the child answer, “Zero!”

Repeat with different objects, such as a block, toy animal, or pom-pom.

Use a short chant:

“One is here, take one away.
Nothing is left—zero today!”

Quick Check

Ask:

• “How many objects did we start with?”
• “How many did we take away?”
• “How many are left?”
• “Can you find the number zero?”

3. We Do: Movement Subtraction

Time: 5 minutes

Have the child stand up. Say:

“You are one jumping frog. Make one jump!”

After the child jumps, say:

“Now the frog hops away. Sit down. How many jumping frogs are left?”

Help the child answer, “Zero.” Repeat with other pretend actions:

• One clap, then stop: “Zero claps are happening now.”
• One toy train moves away: “Zero trains are on the track.”
• One teddy bear goes into the box: “Zero bears are outside the box.”

4. You Do: Child’s Take-Away Challenge

Time: 8 minutes

Give the child a plate and one object. Let the child lead the activity.

Say:

“Show me one. Now take one away. What number tells how many are left?”

Allow the child to choose how to show the answer:

• Point to the number card 0.
• Say “zero.”
• Show empty hands.
• Draw an empty circle or plate.

Repeat the challenge several times with different objects. Give specific feedback:

“You started with one block, moved one block away, and showed zero. You solved it!”

5. Real-World Pretend Play: Snack or Toy Clean-Up

Time: 5 minutes

Choose one pretend situation:

• “There is one cracker. We eat it. How many crackers are left?”
• “There is one toy car. We put it away. How many cars are on the floor?”
• “There is one sticker. We use it. How many stickers are left?”

Have the child act out the situation with a real object or toy. Ask the child to explain:

“I had one. I took one away. Now I have zero.”

6. You Do: Draw the Answer

Time: 5 minutes

Give the child paper and crayons. Draw one large dot, circle, or toy. Ask the child to cross it out or draw it moving away. Then ask the child to draw what is left.

Help the child write or trace:

1 − 1 = 0

The child may decorate the number 0 or draw an empty plate beside it.

Conclusion: Tell What We Learned

Time: 4 minutes

Review the lesson using objects or gestures:

1. Show one object and ask, “How many?”
2. Have the child take it away.
3. Ask, “How many are left?”
4. Show the number 0.

Say together:

“One take away one is zero. When nothing is left, we have zero.”

Exit Question

Ask:

“If you have one balloon and it floats away, how many balloons do you have left?”

Look for the child to say or show zero.

Assessment

Formative Assessment During the Lesson

• Observe whether the child can count one object.
• Ask the child to physically take one object away.
• Check whether the child identifies an empty plate or hand as zero.
• Listen for the phrase “one take away one is zero.”

Summative Assessment: Show Me 1 − 1

Give the child one object and ask them to demonstrate 1 − 1 without help.

Meeting the objective: The child starts with one object, removes it, and shows or says zero.

Developing: The child completes the steps with a reminder or visual support.

Needs more practice: The child needs help understanding that an empty set represents zero.

Differentiation and Support

For a Child Who Needs More Support

• Use only one object at a time.
• Use large, familiar objects and slow movements.
• Repeat the same language: “One here. Take one away. Zero left.”
• Let the child use empty hands to show zero.
• Offer hand-over-hand assistance only when needed.

For a Child Ready for More Challenge

• Ask the child to create their own “one take away one” story.
• Invite the child to draw the number sentence independently.
• Compare two groups: one object on a plate and zero objects on another plate.
• Explore other simple examples, such as 2 − 1 = 1, if the child is ready.

Extension Activities

• Zero Hunt: Look around the home for places with zero items, such as an empty cup or an empty shelf.
• Story Time: Make up a story about one bird flying away and ask how many birds remain.
• Clean-Up Math: Place one toy on the floor, then put it away and say, “Zero toys are on the floor.”
• Number Song: Sing a simple counting song and pause when reaching zero.

Optional Reflection for the Adult

• Did the child understand that taking away the only object leaves nothing?
• Which method helped most: objects, movement, drawing, or pretend play?
• What example can be used next time to revisit zero?