IPAD and APPS for education

I finally have an IPAD that I purchased largely for educational apps for my child with Ds and in anticipation of the upcoming adoption of our 8 year old with a developmental disability.  While there are certainly plenty of apps available, I was largely disappointed.  While there are lots of games to entertain and there is always some learning in games, I haven't found a great deal of teaching that occurs via apps rather more practice and most with very little repetition opportunities.  There just doesn't seem to be enough intermediate steps between advancing from one concept to the next, rather big leaps are made that most typical kids can handle, but my child needs instruction to be broken down into much smaller steps to progress.  I am longing for a online math curriculum that provides small step by step math instruction with loads of repetition once a student is beyond recognizing numbers and number sense and is ready to add and subtract.  There are so many possibilities and simple alterations that could be made to apps and online programs for typically developing kids that would  make a huge difference for our visual/hands on learners.  What I want is an Explode the Code Workbook and online version but one that teaches Math. 

I do very much like the Bob Book series apps.  Great graphics and the practice and spelling component is fabulous.  If you like these, you'll like Explode the Code Online.
BTW, I receive nothing for promoting Explode the Code; I just really like it.