Planning tool

Students:

• solve and model story problems involving addition and subtraction of numbers to 99
• mentally solve problems using strategies such as doubles, near doubles, bridging tens and partitioning
• provide an explanation of how a given solution does or doesn’t work to reach an accurate answer
• use various models to represent addition and subtraction (e.g. bar models, number lines and equations).

Some students may:

• think of the equals sign (=) as ‘here comes the answer’ instead of seeing it as a balance between equivalent statements. To address this, regularly present addition and subtraction problems in different ways. For example, 7 − 5 = ▢ can also be written as ▢ = 7 − 5 or 3 = 7 − ▢.
• not understand the commutative property of addition; that the order of the addends can be changed and it will not affect the answer, which they can draw on when solving additive problems. To address this, explicitly teach this idea using physical materials. Provide opportunities to explore, test and think about whether this property always works.
• not understand the associative property of addition; that it doesn’t matter which order you add numbers when adding three numbers or more. To address this, explicitly teach this idea, explaining how it is useful to make solving problems easier. In 3 + 6 + 7, for instance, adding the 3 and 7 to make 10, and then adding 6 to make 16 can be considered an easier path. Include a focus on these kinds of addition problems during regular classroom talks to support fluency with this idea.
• believe that adding zero (e.g. in 12 + 0) will result in a larger number because they have learnt that ‘adding makes numbers larger’. Similarly, when subtracting zero (e.g. in 12 − 0) they think the answer will be smaller than the minuend. To address this, provide repeated opportunities to explore problems that add and subtract zero.

The Learning from home activities are designed to be used flexibly by teachers, parents and carers, as well as the students themselves. They can be used in a number of ways including to consolidate and extend learning done at school or for home schooling.

Learning intention

• We are learning to solve addition and subtraction problems.

Why are we learning about this?

• We use addition and subtraction in everyday life.

What to do

1. Play with numbers as they come up in the world around you. For example:

• 'I spot a number plate with the numbers 5, 4 and 8 on it. What would those numbers make added together? (5 + 4 + 8)'
• 'I spot the house number 39. I wonder: How many more is 50 than 39? What about 70? Or 100?'

2. Link addition and subtraction to everyday life. For example:

• Talk about situations involving addition and subtraction in storybooks.
• Discuss the scores in a game of sport and talk about the difference between scores. Work out how much the winning team has won by.
• Find opportunities to play with, sort and add up money.
• When shopping, or playing shops, talk about the total number of items in the basket. 'There are 8 apples, 6 bananas and 5 oranges. How many pieces of fruit altogether?'
• Talk about money calculations using whole dollars. 'The milk costs $3, the bread costs $3 and the bananas cost $4. So altogether, how much do we need to pay? If we pay with a $20 note, how much change will we get?'

3. Think about and discuss different ways of solving addition and subtraction. For example, to solve 17 + 6 you might decide to:

• count up from 17 using two jumps of 3 (17 … 20 … 23!)
• break the 6 up into 3 and 3 to ‘make a friendly 20’ (17 + 3 = 20; 20 + 3 = 23)
• start with the known doubles fact of 6 + 6 = 12; then add 11 more to get 23.

Don’t forget that mistakes are a normal part of learning to understand maths. Be curious about mistakes and see them as ways to help you learn. Take plenty of time to solve problems.

Success criteria

I can:

• use strategies such as ‘breaking numbers apart’, ‘using doubles’ and ‘using near doubles’ to help solve addition and subtraction problems
• solve addition problems involving one- and two-digit numbers and explain how I solved them
• solve subtraction problems involving one- and two-digit numbers and explain how I solved them.