Math Fact Master: Addition, Subtraction, Multiplication, and Divisions
These flashcards cost $.99 and cover all four basic operations. The teacher has the ability to control which drills are given to the students. Teachers may also set up challenge sets and view progress reports for each child to use as some sort of assessment.
How it works:
Students log on to the app and select a drill from the set to work on. The interface is fairly simple and easy for young children to navigate, but it is also advanced enough to grow with the child over their learning of basic facts. The students can also monitor their own progress through the use of the progress report functionality.
https://itunes.apple.com/us/app/math-fact-master-addition/id419411014?mt=8