Lesson 95: Addition and subtraction in real life

🧮 MATH (40 Lessons) • 🔵 B. Addition and Subtraction

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Objective

I can use addition and subtraction to solve real-life problems. I can decide when to add (put together) and when to take away and write a simple equation.

Materials

Mini-lesson — When do we add or take away?

In real life, we use addition and subtraction all the time. Stories about toys, snacks, and school can be turned into equations.

When to add

  • We add when we put groups together.
  • Look for words like in all, altogether, more, or joined.
  • Example: "You have 4 toy cars and get 3 more."
  • Equation: 4 + 3 = 7

When to subtract

  • We subtract when we take away or when some are used or eaten.
  • Look for words like left, take away, how many remain, or difference.
  • Example: "You have 9 grapes and eat 2."
  • Equation: 9 − 2 = 7

Reading the story carefully

  • Who or what is the story about?
  • What numbers are in the story?
  • Are we putting together or taking away?
  • What question are we trying to answer?

In this lesson, we will practise turning short stories into equations and deciding if we should add or subtract.

Picture strip: Snack stories — add or take away?

Snacks — Add more

Snacks — Eat some

Guided Practice — Turn stories into equations

You will read short stories and decide if you should add or take away. Then you will write an equation and use the tracing pad to practise key words.

  1. Use real objects: Pick a few toys or snack pieces to act out the story (for example, crayons or blocks).
  2. Story 1 (add): "You have 4 crayons. Your friend gives you 3 more. How many crayons do you have in all?" Use counters to show it, then write 4 + 3 = 7.
  3. Story 2 (take away): "There are 9 stickers on a page. You give 2 to your friend. How many stickers are left?" Use counters, then write 9 − 2 = 7.
  4. Talk through the choice: For each story, say out loud: "I add because we put groups together" or "I subtract because some are taken away."
  5. Make your own story: Make up a school story, like "There are 6 books on a desk. The teacher adds 4 more." Act it out and write the equation.
  6. Use the tracing pad: Trace words like add, take away, left, altogether, or numbers from your equations (such as 7, 9, 10, or 12).
  7. Explain your thinking: Under your equation, write one short sentence to explain, such as "I took away 2, so there are 7 left."
Tracing Pad
Tracing snapshot for print
Tip: After you trace your words, write one short story and its equation, such as "I had 8 grapes and ate 3. 8 − 3 = 5." Draw a tiny picture to match your story.

Practice 1 — Real-life addition stories

[PLACEHOLDER PRACTICE 1]

Practice 2 — Real-life subtraction stories

[PLACEHOLDER PRACTICE 2]

Practice 3 — Choose add or subtract

[PLACEHOLDER PRACTICE 3]

Quick Check — Addition and subtraction in real life

Answer each question about real-life stories. Decide if you should add or subtract. You may use counters or draw a quick picture.

1) When do we usually add in a story?

We add when we put groups together to find how many in all.

2) When do we usually subtract in a story?

Subtraction is used when something is taken away or used up.

3) "You have 5 marbles. You find 4 more." Which equation matches the story?

You are getting more, so you add: 5 + 4 = 9.

4) "There are 10 cookies on a plate. You eat 3." What should you do?

Some cookies are eaten, so you subtract: 10 − 3.

5) "There are 7 books in a basket. The teacher puts in 2 more." How many books are in the basket now?

7 + 2 = 9 books in all.

6) "You have 12 crayons. 4 crayons roll away." How many crayons are left?

12 − 4 = 8 crayons left.

7) Which words tell you to add?

"In all", "altogether", and "more" usually mean add.

8) Which words tell you to subtract?

"Left", "take away", and "how many remain" usually mean subtract.

9) "There are 8 toy cars. 3 are red and the rest are blue." Which equation finds how many blue cars there are?

8 total minus 3 red tells how many are blue.

10) "You read 6 pages in the morning and 5 pages at night." How many pages did you read in all?

6 + 5 = 11 pages in all.

11) "There are 15 children on the playground. 7 children go inside." How many children are still on the playground?

15 − 7 = 8 children still outside.

12) Which equation shows a real-life addition problem?

9 + 4 = 13 is an addition equation.

13) "You had 10 balloons. 3 balloons popped." Which equation matches the story?

Some balloons are gone, so you subtract: 10 − 3 = 7.

14) What is the difference in 14 − 5?

14 − 5 = 9, so the difference is 9.

15) Why is it important to read the whole story before solving?

Reading carefully helps you decide if the story needs addition or subtraction.

Assessment (parent/teacher)

Exit ticket (student)

Next time I will practise…

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