Maths
Work through the power points and worksheets for quarters first and then thirds.
English
Look at the features of an explanation text, the look at the 3 example documents, read through them and see how many of the features you can spot. You may not find them all so just focus on the ones you can.
Then using these examples to have a go at planning your own explanation text. First decide what you want to do it on and then use the planning document to plan your own.