I found a company, Bettermarks GmbH, who offers both online and apps for the iPad. They make apps covering fractions, geometry, data and a few other topics in both English and German.
I stumbled across this company when I down loaded the 2nd app on fractions. The app is set up with prerequisite topics and then has 3 "chapters" for the student to work through. What I like is even if the student is correct, they can still get an explanation to make sure. If they miss the problem, it provides an explanation.
Last night I downloaded almost every one of the free apps they offer because I would like to check them out to see how well they will fit into my class.
Their website indicates they have created adaptive mathematics for grades 4 to 10. Honestly, I plan to spend time throughout the week, checking these products out and I will be happy to give a more indepth report later on.
I just found out the only difference between the free and paid apps is that the paid apps have no apps.