Adding, Subtracting and Equal Groups: Year 2 Study Guide
Year 2 builds flexible mental strategies and the first ideas of multiplication and division.
Children add and subtract using strategies such as partitioning, jump strategy on a number line, and compensation (rounding then adjusting). They also solve problems about equal groups and sharing using drawings and repeated addition.
Choosing a good strategy is more important than using the same method every time. 99 + 46 is easier as 100 + 46 − 1 = 145.
Strategies for adding and subtracting
| Strategy | How it works | Example |
|---|---|---|
| Partitioning | Split into tens and ones | 34 + 25 → 30 + 20 + 4 + 5 = 59 |
| Jump strategy | Hop along a number line | 47 + 26 → +20 → 67 → +6 → 73 |
| Compensation | Round then adjust | 58 + 19 → 58 + 20 − 1 = 77 |
| Make 100 | Add to the next hundred | 100 − 64 → 64 + 36 = 100 |
Equal groups and sharing
Equal groups: 4 bags with 5 apples in each bag is 5 + 5 + 5 + 5 = 20 apples. Sharing: 12 biscuits shared equally among 3 children gives 4 each. Children first draw and count, then skip count, and later use multiplication facts. The words 'each', 'every' and 'equal' signal these problems.
Are there equal groups?
Circles or bars.
5, 10, 15, 20.
20 apples.
Inverse operations
Addition and subtraction undo each other: if 36 + 28 = 64, then 64 − 28 = 36 and 64 − 36 = 28. A fact family shows all four related facts. Use this to check your work or to solve missing number problems such as ? + 28 = 64.
Worked examples and common mistakes
Example: 83 − 47. Count on from 47 to 50 (3), then to 80 (30), then to 83 (3): 36. Example: 15 stickers shared among 5 friends is 3 each. Common mistakes: subtracting the smaller digit from the larger in each column, forgetting that 'sharing' means equal parts and not checking whether an answer is reasonable. Estimate first.
Check your understanding: model answers
1. 59 + 36 → 60 + 36 − 1 = 95. 2. 36. 3. 20 ÷ 4 = 5 biscuits each.
✨ Key Takeaways
- Use partitioning, jumps or compensation.
- Equal groups lead to multiplication; sharing leads to division.
- Fact families link addition and subtraction.
- Estimate to check.
💬 Questions for Discussion & Reflection
- Find 59 + 36 using compensation.
- Find 100 − 64.
- 20 biscuits are shared among 4 children. How many each?