Add across 10
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Add across 10: skill guide
| Objective | Learners will be able to add two single-digit numbers with a sum from 11 to 18 by filling a ten strip to 10 and adding what is left. |
|---|---|
| Grade | Grade 1 |
| Standard | CCSS.MATH.CONTENT.1.OA.C.6 |
| Difficulty | Developing · Mixed |
| Representation | Ten strip, Numerical equation |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
Learners will be able to add two single-digit numbers with a sum from 11 to 18 by filling a ten strip to 10 and adding what is left.
What this practice covers
Each problem shows two ten strips and an equation such as 7 + 6. The dots for the first number fill part of the first strip. The dots for the second number, in another color, finish that strip and continue into the next one. The learner finds the total and taps it from five choices. The first number is from 4 to 9, the second is from 3 to 9, and every sum is from 11 to 18.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.1.OA.C.6 — Add and subtract within 20 using strategies such as making ten.
Who it’s for
This practice is for Grade 1 learners who know the pairs that make 10 and are ready to add past 10. It also suits older learners who still count on by ones for sums like 7 + 6.
What to know first
- Learners should count reliably, read two-digit numerals, and understand addition as joining parts. Each problem shows the sum on ten strips.
Difficulty and scaffolding
Developing · Mixed stage
Problem representations
- Ten strip
- Numerical equation
Three worked examples
- For 9 + 4, 1 of the 4 dots fills the first strip to 10. The other 3 dots go in the next strip, so 9 + 4 = 13.
- For 6 + 8, 4 of the 8 dots fill the first strip to 10. The other 4 dots go in the next strip, so 6 + 8 = 14.
- For 8 + 9, 2 of the 9 dots fill the first strip to 10. The other 7 dots go in the next strip, so 8 + 9 = 17.
Likely misconceptions
- Learners may count every dot from one, or count on by ones and lose track as they pass 10. Have them see how many dots finish the first strip, then count the dots left in the next strip.
Hints and explanations
- For 9 + 4, 1 of the 4 dots fills the first strip to 10. The other 3 dots go in the next strip, so 9 + 4 = 13.
- For 6 + 8, 4 of the 8 dots fill the first strip to 10. The other 4 dots go in the next strip, so 6 + 8 = 14.
- For 8 + 9, 2 of the 9 dots fill the first strip to 10. The other 7 dots go in the next strip, so 8 + 9 = 17.
What to practice next
Next, Add numbers across 10 asks for the same kind of sums with numerals only and no ten strips.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Add across 10 FAQs
What is the goal of add across 10?
The goal is to add past 10 by making 10 first. A learner should be able to say how many dots finish the first strip, how many are left, and what 10 plus that amount makes.
Should this practice be timed?
No timer is required. First build accurate, understandable strategies. Speed usually improves as learners know the pairs that make 10 and can split the second number quickly.
What should a learner do after a mistake?
After a wrong answer, the learner gets a second try. Count how many dots finish the first strip, then count the dots in the next strip and add them to 10. A short explanation helps more than a quick second guess.
How many problems should be completed at once?
A Quick check has 5 problems and a Practice session has 15. A learner may pause when attention drops. A short, successful session with clear reasoning is more useful than rushing through a longer one.