The Khan Academy is a well-known, free, on-line database of instructional videos that cover a wide range of subjects.
This particular app was designed by Ximarc Studios and presents 20 videos from the Khan Academy covering the subject of Calculus 1. The videos are arranged in a proper sequence for learning and are very easy to follow.
This application is a great study companion for anyone who is taking introductory calculus in high school. As one who has studied calculus in the past, I can tell you that this arrangement of videos is sure to fill in some gaps in understanding that you will get from traditional school instruction.
The video series starts with a why are we doing this in the first place type intro and a good basis for the subsequent videos.
Get this app and may you never know the horrors of calculus that I have seen.
Requires iOS 5.1 or later. Compatible with iPhone, iPad, and iPod touch.