#### Unit Plan

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\$15.99 or Free on Plus | 8 x Lessons |1 x Assessment | Suitable for Grade: 3

This Mathematics unit covers a range of mental computation strategies for addition.

It consists of 8 lessons of approximately 60-minutes duration.

The sequence of lessons and suggested time frames should be regarded as a guide only; teachers should pace lessons in accordance with the individual learning needs of their class.

An assessment task for monitoring student understanding of the unit objectives is included and will require an additional lesson.

### Overview

#### Objectives

• To reinforce student understanding of basic addition principles, using concrete materials.
• To recall 'friends of ten' facts and use this knowledge to solve addition sums.
• To explore the jump strategy for adding two- and three-digit numbers.
• To explore the use of number boards/hundreds charts when adding numbers.
• To progress student understanding of mental addition by partitioning numbers into place value to help them find a total.
• To investigate the relationship between addition and subtraction.
• To build upon students' understanding of addition and subtraction by exploring compensation.
• To reinforce that students can choose to use different addition strategies in different situations.

#### Preparing for Learning

Addition Detectives is themed as an investigation in which students will uncover a new suspect at the end of each lesson. The unit concludes with the students narrowing down the list of suspects until only one remains.

Prior to commencing the unit, familiarise yourself with the Addition Detectives – Teaching PresentationThis presentation contains a consolidation activity for each lesson and will reveal the new suspects.

Create a display in the classroom by printing the Suspect Board Wall Display. Place the banner in a central location and put the pictures of the suspects in a large envelope (or similar), ready to add them to the display during each lesson.

This unit covers a range of addition concepts and strategies that increase in complexity. Teachers are encouraged to browse each lesson before beginning the unit and to adapt the lessons and teaching resources to suit the needs of their students.

### Lessons

#### Concrete Materials

A 60-minute lesson to reinforce students' understanding of basic addition principles, using concrete materials.

#### Bridging to Ten

A 60-minute lesson designed for students to recall 'friends of ten' facts and use this knowledge to solve addition sums.

#### Jump Strategy

A 60-minute lesson designed to explore the jump strategy for adding two- and three-digit numbers.

#### Number Boards

A 60-minute lesson designed to explore the use of number boards/hundreds charts when adding numbers.

#### Split Strategy

A 60-minute lesson designed to progress students' understanding of mental addition by partitioning numbers into place value to help them find a total.

##### Lesson 6

A 60-minute lesson designed to investigate the relationship between addition and subtraction.

#### Compensation Strategy

A 60-minute lesson designed to build upon students' understanding of addition and subtraction by exploring compensation.

##### Lesson 8

A 60-minute lesson designed to reinforce that students can choose to use different addition strategies in different situations.

##### Lesson 9 (Assessment)

A 30-minute assessment designed to assess students' understanding of working with place value to solve problems, the connection between addition and subtraction, and the development of efficient mental strategies for computation.

#### Australian Curriculum alignment

• ACMNA053

Apply place value to partition, rearrange and regroup numbers to at least 10 000 to assist calculations and solve problems

• ACMNA054

Recognise and explain the connection between addition and subtraction

• ACMNA055

Recall addition facts for single-digit numbers and related subtraction facts to develop increasingly efficient mental strategies for computation