My daughter with learning differences went through the 5+ algebra game on a Saturday afternoon. When she finished I could write simple algebraic equations which she could solve for me. She was in 4th grade at the time and we were able to use the app to show her school that she could do more than the single digit addition problems they made her repeat over and over. By 5th grade we were able to get her into grade level math and now she is just finishing 7th grade algebra. She started using the older algebra app and the geometry app independently. Can you write an app for calculus next?