Below is a PowerPoint which does have a nice visual for you, modelling the process with bars so you can see what is happening. However, this does not give you guys a good format for recording and working out problems for yourself. I have recorded videos to go along with the questions in that PowerPoint, giving you a format for your books. Please watch those and please follow that format.
Also, I have put a couple of guidance videos for the tasks in a subpage too, except for the last one. If you are attempting that challenge, have a go first but if you follow through to the second subpage I have typed up some hints for you to follow.