Math Ref is a great math reference application that teachers and students can use to access over 1,400 mathematical formulas, figures, and equations on the fly. Available for Apple devices, it can be purchased from App store for $0.99 cents. Math Ref is a handy and affordable mobile reference for: Algebra, Geometry, Trigonometry, Calculus, Physics, and more.
Statistical Free is an easy-to-use app you can use to do quick statistical analyses on your mobile device. Simply enter a data-set into the app, then click the Statistics button to view measures of central tendency and correlation. You can also visualize your data as a bar graph, scatter plot, and z-score/percentile.
The videos at the Khan Academy, a free educational resource, can be used as a supplement or remedial review to strengthen student comprehension of difficult topics in math and science. With the Khan Academy Statistics app, a complete library of introductory statistics lesson videos are downloaded to your iPhone or iPad for easy on-demand access.