Addition Within 20
Sample 1 · Seed leaf-15-1-addition-within-20-sample-a7
1. 18 + 0 = ___
2. 3 + 6 = ___
3. Find the sum: 0 + 15
4. Solve: ___ = 6 + 14
1st GradeAddition1.OA.C.6
Addition Within 20 Worksheets for 1st Grade
These addition within 20 worksheets give parents and teachers focused, repeatable practice for 1st Grade learners. Use counting-on, making-ten, and decomposition strategies to add within 20. Choose a fixed-seed sample or make a fresh printable without creating an account.
Learning objective: Use counting-on, making-ten, and decomposition strategies to add within 20.
Reproducible fixed seeds
Three free worksheet samples
Open a sample to preview all questions, make a fresh version, or download the worksheet and answer key.
Addition Within 20
Sample 2 · Seed leaf-15-1-addition-within-20-sample-m3
1. 17 + 1 = ___
2. Solve: ___ = 12 + 8
3. Find the sum: 1 + 3
4. 5 + 7 = ___
Addition Within 20
Sample 3 · Seed leaf-15-1-addition-within-20-sample-z9
1. Find the sum: 8 + 12
2. Solve: ___ = 9 + 7
3. 10 + 5 = ___
4. Solve: ___ = 7 + 1
One fixed-seed example
How to approach this skill
Problem: 18 + 0 = ___
Answer: 18
Strategy: Combine the quantities and check that the sum is reasonable for the stated range. This example supports the page objective: Use counting-on, making-ten, and decomposition strategies to add within 20.
How to use this worksheet
- Encourage a strategy such as making ten, decomposing, or using place value. For this addition within 20 set, begin without a timer.
- Check a few answers by reversing the operation with subtraction. Regenerate only when the learner is ready for another arrangement of the same objective.
Begin with the easy setting when the strategy is new, use standard for independent practice, and reserve challenge for a learner who can explain the method accurately.
Common mistakes to watch
- Losing track of a regrouped ten when working vertically. Watch for this specifically during addition within 20 practice.
- Adding digits from different place-value columns. Use the worked correction as the next teaching example.
Use the answer key to find a pattern, then ask the learner to explain one corrected example rather than repeating an entire set immediately.
Standards reference
Skill alignment
Alignment labels identify the primary skill practiced. A worksheet is supplemental practice and does not assess every part of a standard.
Planning help
Frequently asked questions
What does this 1st Grade Addition Within 20 worksheet practice?
Use counting-on, making-ten, and decomposition strategies to add within 20.
How should adults use the Addition Within 20 printable?
Start with one untimed set, review the learner's strategy, and use the answer key to discuss errors. Generate a new fixed-seed set only after the current skill is understood.
Does the Addition Within 20 download include answers?
Yes. The free PDF can include an appended answer key, or the answer key can be downloaded separately for adult use.
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