No sound and difficult to read

This app has not been prepared well for use on an iPhone.

I have tried several different videos in both the Calc 1 and 2 apps; neither have had any sound. This is particularly frustrating in videos where the writing is too small and pixilated to read on an iPhone screen.

I know Khan Academy has some good content, as I have viewed tutorials on my computer, but this App is terribly lacking.

Book_girl about Khan Academy: Calculus 1