VEX Robotics has their own in-house developed software for both VEX IQ and VEX V5, named VEXcode.
If you or your students have limited coding experience, we would recommend VEXcode IQ Blocks, or VEXcode V5 Blocks (depending on your platform). VEXcode Blocks provides an easy to use interface, with built-in tutorials, sample programs, and help.
For more experienced programmers, we would recommend using VEXcode IQ Text or VEXcode V5 Text. Similar to VEXcode Blocks, this program has built-in tutorials, sample programs, and help.
Note: VEXcode is the only officially VEX-supported programming software. Other third party programs include ROBOTC, PROS, Robot Mesh Studio, MATLAB, and easyC.