Rating: Excellent
Platform: iPhone/iPad/Android
Cost: Free
Strong Points: Intuitive interface, almost no lag between inputting an equation and seeing the graphed output.
GeoGebra 3D Calculator is an excellent app for educators, students, and casual mathematicians. Users can easily input any equation with a keyboard that includes numerous functions, variables, and mathematical symbols. Equations pop up immediately in the viewer, which shows a 3D representation of the plot. The graph is also interactive, allowing users to view the plot from multiple angles. Equations can be saved and exported and even viewed in augmented reality. In addition to the graphing function, the app includes numerous premade graphs that cover topics such as surface area, volume, and even the alignment of planets in the solar system. For educators, the app includes an exam mode that prevents students from exiting the calculator and seeking answers elsewhere for the duration of the exam. GeoGebra 3D Calculator is an excellent resource for math class and a great low-cost alternative to expensive graphing calculators.