- Define and explain Subtracting Objects in your own words
- Use key terms such as Difference accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
This lesson focuses on Subtracting Objects: take some away and count what is left to find the difference.
Take some away and count what is left to find the difference.
Key ideas
Counting all
Put two groups together and count everything from the start to find the total. This works well with small numbers and real objects like beads or blocks.
Counting on and back
Start from the first number and count on for addition, or count back for subtraction. This is much quicker than counting everything from 1 each time.
Key term — Difference: The answer when you subtract. It also tells you how far apart two numbers are, so the difference between 9 and 4 is 5.
Lila has 7 pennies. Her grandma gives her 6 more. Then she spends 4 pennies. How many does she have left?
Add the gift: 7 + 6 = 13. Subtract the spending: 13 − 4 = 9.
Answer: 9 pennies.
- Subtracting the bigger number from the smaller Always check which number you start from — 9 − 5 is not the same as 5 − 9.
- Forgetting to count on from the bigger number Start at the larger number and count on the smaller jump to save steps and avoid slips.
Practice
12 — start at 7, then count on: 8, 9, 10, 11, 12.
9 — count back: 14, 13, 12, 11, 10, 9.
6 — 4 + 6 = 10.
14 — 9 + 5 = 14.
Quick check
Which of these best defines "Difference"?
Write the fact family for 6, 9 and 15.
20 − 8 = ?
- Subtracting Objects: take some away and count what is left to find the difference.
- Counting all: Put two groups together and count everything from the start to find the total.
- Sum: The answer when you add numbers together.
- Watch out for: subtracting the bigger number from the smaller