Teaching points

• Teaching point 1: Addition of three addends can be described by an aggregation story with three parts.
   
• Teaching point 2: Addition of three addends can be described by an augmentation story with a ‘first…, then…, then…, now…’ structure.
   
• Teaching point 3: The order in which addends (parts) are added or grouped does not change the sum (associative and commutative laws).
   
• Teaching point 4: When we are adding three numbers, we choose the most efficient order in which to add them, including identifying two addends that make ten (combining).
   
• Teaching point 5: We can add two numbers which bridge the tens boundary by using a ‘make ten’ strategy.
   
• Teaching point 6: We can subtract across the tens boundary by subtracting through ten or subtracting from ten.