Adding and SubtractingOperations (Calculating)

Now and Next: Addition

Where are they now?

Uses doubles and near doubles strategy to mentally add selected 1 and 2-digit numbers ( eg, 8 and 9, 15 and 16)

Use formal notation to record equations

Where to next?

Uses make-to-ten strategy to mentally add single digit numbers and beyond ( eg, 8 and 6, 18 and 6) Solves 2 digit addition problems with support , eg model 28 + 36 using MAB, 10 frames or Open Number Lines

Now and Next: Subtraction

Where are they now?

Uses count on from (think of addition) strategy to solve difference problems involving numbers to 20 eg understand 13 – 11 is the same as saying 11 + placeholder = 13
Use formal notation to record equations

Where to next?

Uses make-back-to-ten, halving and/or place-value-based strategies to mentally subtract single digit numbers from 1 and 2-digit numbers
Solves 2 digit subtraction problems with support (eg, MAB and Open Number Lines)

Purpose

Addition and subtraction are an important part of the skill set of a numerate person and are foundational skills for the other operations (multiplication and division) as well as for the larger body of mathematics.

Building Addition and Subtraction skills:

The skill of adding and subtracting draws on all of the skills studied in the whole number section, and a failure to progress will generally indicate that one or more of these skills needs to be revisited.

Understanding addition and subtraction begins with the realisation that the total of a collection changes when items are added or removed. The key skill at this stage is still counting, as students will initially use a 'make all- count all' strategy. That is, they will either add or remove a specified number of items from their collection, and then count the new collection starting at one to find the new total. Language is an important element at this level - linkng the idea of adding and removing items from a collection should be linked with words such as add, plus, take, minus and subtract and difference*.

Once students are familiar enough with counting to 'trust the count' they will be able to add and subtract by counting on or back from the total. This is a very inefficient way of adding and subtracting however and as soon as students 'trust the count', they should start to explore patterns. These will be visual initially, through subitising and investigating the 'part-part-whole' nature of number using counters.

Part-part-whole knowledge begins with exploring the structure of all the numbers to 10 - understanding that four is two and two or three and one for example. Part-part-whole knowledge can then be extended to larger numbers through an understanding of the base 10 and place value system ultimately leading to efficient mental methods of adding and subtracting.

*Difference is an important idea as it leads to the understanding that add and subtract are just two different ways of looking at the same thing. Addition and subtraction should be taught as part of a single concept where possible.

Resources

Many of these activities are the same as those in the Part-Part-Whole section as the core concepts are identical. There is an added emphasis her on connecting these ideas to the language of addition and subtraction however.

 

Linked activitiesLinked Activities

  • download Ten Frames Addition Bingo (video example)
  • download Race to the 90s and back
  • download Seven Card Addition
  • download 100 Straw Subtract
  • download Long Walk, Short Pier
  • download Salute

AssessmentAssessment

  • download Add and Subtract 6

other resources References to Other Resources

 

 

Activities and Assessments

 

download Ten Frames Addition Bingo (video example)

Ten Frames Addition Bingo (video example)

Focus: Building and consolidating a 'make to 10' stragegy to facilitate the rapid mental addition of two single digit numbers with carrying.

How: See Ten Frames Addition Bingo instruction sheet or view the video

Video of teacher modelling:

video English

video Djambarrpuyŋu

video Kriol

Download Ten Frames Addition Bingo instruction sheet

Download Ten Frames Addition Bingo board

Download Ten Frames

Download Spinners


download Race past 90 and Back

Race past 90 and Back

Focus: Adding and subtracting two digit numbers to and from two-digit numbers with support (modified hundred chart).

How: See Race past 90 and Back instruction sheet

Download Race past 90 and Back game board

Download Spinner 0-9

Download Spinner 0-30

 

download Seven Card Addition

Seven Card Addition

Focus: Finding the total of multiple single digit numbers by first identifying pairs to 10.

How: See Seven Card Addition instructions

Download Seven Card Addition score

Download Numeral Cards 1-9

 

download 120 Straw subtract

120 Straw subtract 

Focus: Subtracting 2 digit numbers from 2 digit numbers with support (bundled straws).

How: See 100 Straw Subtract instructions

Download 100 Straw Subtract score sheet

Download Spinner 0-30

Download Spinner 0-9

download Long Walk, Short Pier

Long Walk, Short Pier 

Focus: Adding and subtracting 1 and 2 digit numbers to and from 2 digit numbers with support (number lines).

How: See Long Walk, Short Pier instructions

Download Long Walk, Short Pier game board

Download Long Walk, Short Pier markers

Download Spinner +/-

Download Spinner 0-20

Download Spinner 0-9

download Salute

Salute 

Focus: For the Players: Solving "difference" or "missing addend" problems for totals to 20 without the use of counters or visual cues; For the Dealer: Finding the total of two numerals (each in the range to 10) by using doubles, near doubles and part-part-whole knowledge.

How: See Salute instructions

Use playing cards or:

Download Numeral cards to 10

 

download Assessment Points: Add / Subtract 6

Add / Subtract 6

Activity based indicators that students have achieved the target understandings

Download Assessment Points - Add / Subtract 6 sheet

 

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