 solve problems with addition and subtraction:
 using concrete objects and pictorial representations, including those involving
numbers, quantities and measures
 applying their increasing knowledge of mental and written methods
 recall and use addition and subtraction facts to 20 fluently, and derive and use
related facts up to 100
 add and subtract numbers using concrete objects, pictorial representations, and
mentally, including:
 a two-digit number and ones
 a two-digit number and tens
 two two-digit numbers
 adding three one-digit numbers
 show that addition of two numbers can be done in any order (commutative) and
subtraction of one number from another cannot
 recognise and use the inverse relationship between addition and subtraction and use
this to check calculations and solve missing number problems.

50 minutes per week in class, and maybe some time outside of class.