A lot of problems are caused by adverse learning in primary and early secondary. It's essential the student knows how to add two digits together e.g 7 + 8 and also essential they know their times tables. Although I will recap these in lessons i.e. reinforce these basic number facts, it is more cost effective if you work on them as well.
I am currently developing some web based programs to assist you in this task. These will be provided as a free service.Watch this space!
To parents I would say:- don't assume your child knows these! Try testing them out yourself.