Final answer:
A student using a radio controller to communicate with a small robot is primarily an example of human to machine communication, although machine to machine elements could also be present.
Step-by-step explanation:
A student using a radio controller to communicate with a small robot is an example of human to machine and machine to machine communication. The human uses the controller to send commands to the robot, which is the human to machine aspect. The robot might also communicate with other machines or systems autonomously, completing the machine to machine communication circle, if it's designed that way. Still, based on the information provided, this situation primarily represents human to machine communication, as the student is directly controlling the robot via a controller.