Let's look at today's problem.
What is the whole length that Lulu wants to swim?
What do we already know and what do we still need to find out?
That's right we know she has swum 35m but needs to get to 50m.
Shall we use a subtraction or an addition to work this out?
That's right we needed a subtraction
50 - 35 = 15
Let's try another together.
Do we need and addition or a subtraction?
That's right we want to know the total amount of cloth so that is an addition.
You need to think carefully about if you should add or subtract the numbers.
If you are in school turn to page 171 and 172.
If you are at home write the calculation and answer in your blended learning book.