Compatible Numbers

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Achievement Objectives
NA2-1: Use simple additive strategies with whole numbers and fractions.
Specific Learning Outcomes

Solve addition problems by using compatible numbers.

Description of Mathematics

Number Framework Stage 5.

Required Resource Materials
counters
Activity

Using Materials

Problem: Tina has 6 tomatoes, Miriam has 2 tomatoes and Liam has 3 tomatoes. They use 9 tomatoes for a salad. How many tomatoes are left?

Discuss how to record the problem then record 6 + 2 + 3 - 9 on the board. The students model piles of 6, 2 and 3 counters. Discuss which two piles make 9 and remove them to leave 2. Record 2 on the board.

Examples: Word stories and recording for: 5 + 2 + 5 – 10, 9 + 5 +1 – 6, 8 + 2 + 7 – 9, 4 + 5 – 9, 3 + 5 + 5 – 8, 4 + 6 + 4 + 3 - 7….

Using Imaging

Examples: Word stories and recording for: 4 + 2 + 5 – 9, 8 + 5 + 2 – 7, 10 + 2 + 7  - 12, 10 + 5 – 15, 3 + 2 + 6 – 5, 2 + 6 + 4 + 3 - 7

Using Number Properties

Examples. Write these numbers on paper and cross out pairs and the numbers subtracted to get the answers: 8 + 6 + 4 – 10, 7 + 8 + 2 – 9, 7+ 3 + 3 + 7 - 10 – 10, 1 + 2 + 5 + 2 - 7 – 3, 9 + 6 + 4 - 7 - 2 ….

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Level Two