Number Operations (Addition… · B3 Mathematics

Lesson notes

Learning Objectives

Indicator: B3.1.2.1.1 - Use standard strategy or procedure to do addition or subtraction within 1000

By the end of the lesson, learners can:

Explain that a symbol such as ☐ or _ in a number sentence stands for an unknown value that must be found.
Solve addition number sentences with one unknown within 1000 using the standard column method, showing each step clearly.
Solve subtraction number sentences with one unknown within 1000 using the standard column method, showing each step clearly.
Create their own addition or subtraction question with one unknown for a classmate to solve.
Justify the strategy they used by explaining why they added or subtracted to find the unknown value.

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Curriculum details

Strand: Number (Strand 1)
Sub-strand: Number Operations (Addition, Subtraction, Multiplication and Division) (1.2)
Content standard: B3.1.2.1 - Develop and use standard strategies for adding and subtracting within 1000
Indicator: B3.1.2.1.1 - Use standard strategy or procedure to do addition or subtraction within 1000
Suggested placement: Term 1, Week 8 (Week 8 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: Mathematics Curriculum for Primary Schools (Basic 1-3), 2019, p. 48
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g. 1. Explain the purpose of a symbol like a square or an underline in a given addition or subtraction mathematics sentences with one unknown (e.g.: 227 + ☐ = 609)
E.g. 2. Create an addition or subtraction question with an unknown for a classmate to solve, and using either ☐ or ___ to represent the unknown
E.g. 3. Solve an addition or subtraction question with one unknown, using a variety of strategies and explaining the strategy used.
E.g. 4. Use the methods of decomposition to find the sums and difference of numbers within 1000