Addition Detectives

Teach Starter Publishing
9 x lessons | Suitable for years: 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.

Login to view the Unit plan.


  • AC9M3N03

    Add and subtract two- and three-digit numbers using place value to partition, rearrange and regroup numbers to assist in calculations without a calculator

  • AC9M3A01

    Recognise and explain the connection between addition and subtraction as inverse operations, apply to partition numbers and find unknown values in number sentences

  • AC9M3A02

    Extend and apply knowledge of addition and subtraction facts to 20 to develop efficient mental strategies for computation with larger numbers without a calculator

Teach Starter Publishing

Teach Starter Publishing

We create premium quality, downloadable teaching resources for primary/elementary school teachers that make classrooms buzz!

Find more resources like this


Write a review to help other teachers and parents like yourself. If you'd like to request a change to this resource, or report an error, select the corresponding tab above.

Log in to comment
  • Karina Ferguson

    My students ADORED this unit. If more maths units like this could be put together, that would be amazing!

    • Tom (Teach Starter)

      Hi Karina, Thank you so much for your lovely feedback! I am so glad your students enjoyed uncovering the mystery in the Addition Detectives unit. We will definitely take your suggestion into consideration when making our future units! Thanks again!

  • Paul (Teach Starter)

    Hi Joanne, The link is now included in the text of the lesson plan. Clicking on the hyperlink should take you directly to the video.