Grade 1, Operations
Subtract within 20
Subtract within 20, first without and then with bridging 10.
Three levels
One skill, rising difficulty
Each sheet carries one level. The three are the same skill at rising difficulty, each named for what it practises.
- Level 1: No bridging 10
- Subtract.
- Level 2: Bridging 10
- Subtract. Go back to 10 to help you.
- Level 3: Missing number
- Write the missing number.
Worked example
How the sheet explains it
The helper printed at the top of each sheet: one solved example and the steps a student follows, before the first question. Every number sentence in it is proven by the same checker as the answer key.
Level 1: No bridging 10
17 − 4 = 13
- 17 is 10 and 7.
- Take away from the ones: 7 − 4 = 3.
- Then 10 + 3 = 13, so 17 − 4 = 13.
Level 2: Bridging 10
13 − 5 = 8
- 13 is 10 and 3. Take away 3 first: 13 − 3 = 10.
- You still have 2 more to take away, because 5 = 3 + 2.
- 10 − 2 = 8, so 13 − 5 = 8.
Level 3: Missing number
14 − 8 = 6
- Add up instead. Count up from 6 to 10. That is 4.
- Count up from 10 to 14. That is 4 more.
- 4 + 4 = 8, so 14 − 8 = 6.
- If the first number is missing, add the other two.
Goes with
Reference sheets
One-page helpers a student keeps beside this sheet:
- Ways to make 10
- Addition and subtraction strategies
- Addition chart
Every reference, facts and support sheet is listed in the worksheet catalogue.
In the BC curriculum
Content standards
The British Columbia content standards this skill is written for, by the codes used across this site:
- bc.math.1.c.3
- bc.math.2.c.3
The wording of each standard is on the Province's mathematics curriculum page.
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