Complements of 10 with ten strips
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Complements of 10 with ten strips: skill guide
| Objective | This practice shows every complement pair inside a one-row ten strip. |
|---|---|
| Grade | Kindergarten |
| Standard | CCSS.MATH.CONTENT.K.OA.A.4 |
| Difficulty | Foundational · Representational |
| Representation | Ten strip |
| Practice format | Interactive, account-free practice with immediate feedback |
Objective
This practice shows every complement pair inside a one-row ten strip.
What this practice covers
This practice shows every complement pair inside a one-row ten strip. Red dots begin at the left and green dots make the rest of the strip to ten. A stronger divider after the fifth space provides a reliable landmark. Learners can identify the green complement by counting on from the red group, subtracting the red amount from ten, or using a remembered number bond. The one-row arrangement also makes the two parts look like lengths that combine to form a whole.
Standards alignment
Supports Common Core: CCSS.MATH.CONTENT.K.OA.A.4 — For any number from 1 to 9, find the number that makes 10.
Who it’s for
It is designed for kindergarten learners who have already met ten frames and are ready to recognize the same number relationships in a different arrangement. Changing the model helps confirm that a number bond remains true even when its visual layout changes.
What to know first
- Learners should understand that the strip always contains ten dots in total and that the two colors represent two parts of that total. Familiarity with the pairs that make five provides a helpful foundation, because the midpoint splits the strip into two groups of five.
Difficulty and scaffolding
Foundational · Representational stage
Problem representations
- Ten strip
Three worked examples
- With 4 red dots, 6 green dots make the rest of the strip. You can see one more to reach the midpoint and five more after it: 4 + 6 = 10.
- With 8 red dots, only 2 green dots remain at the right end. Thinking backward from ten gives 10 − 8 = 2.
- With no red dots, all 10 dots are green. Zero and ten are also a complement pair: 0 + 10 = 10.
Likely misconceptions
- Learners may count the stronger midpoint line as an object, answer with the red group, or overlook green dots on the far side of the divider. Count only circles and check the color named in the prompt. The final check is always the same: red dots plus green dots must equal ten.
Hints and explanations
- With 4 red dots, 6 green dots make the rest of the strip. You can see one more to reach the midpoint and five more after it: 4 + 6 = 10.
- With 8 red dots, only 2 green dots remain at the right end. Thinking backward from ten gives 10 − 8 = 2.
- With no red dots, all 10 dots are green. Zero and ten are also a complement pair: 0 + 10 = 10.
What to practice next
Move from pictures to number-bond diagrams and missing-addend equations. Then use complements to solve addition facts that cross ten, such as 9 + 4, and subtraction facts that begin at ten, such as 10 − 6.
Editorial review
Reviewed by Brilliant’s curriculum team. Exercises are generated within defined difficulty ranges and checked against verified answer rules.
Complements of 10 with ten strips FAQs
How is this different from the ten-frame version?
The mathematics is the same, but the arrangement changes. A ten frame groups dots into two rows of five, while a ten strip places all ten dots in one row. Seeing both models helps learners recognize the number bond rather than memorizing one picture.
How should a learner use the midpoint line?
Treat the line after the fifth space as a landmark, not as something to count. A learner can quickly see whether the red group stops before five, at five, or after five, then reason about how many green dots are needed to reach ten.
Can complements of 10 be found with subtraction?
Yes. If the strip shows 7 red dots, the green complement can be found with 10 − 7 = 3. Addition and subtraction describe the same part-whole relationship here: 7 + 3 = 10 and 10 − 7 = 3.
How many problems should a learner practice at once?
A focused set of about 10–15 problems is usually enough for useful practice without fatigue. Stop earlier if attention or accuracy drops. Several calm sessions spread across a week are more effective than one long session. This activity offers a five-question quick check and a fifteen-question practice with immediate feedback after every answer.
What should a learner do after visual models?
Ask the same questions with a number bond or equation and keep the strip available if support is needed. Gradually remove the picture as recall strengthens. The goal is flexible use of the relationship, not speed before understanding.