I think most instructors would agree that it is much easier to teach someone using a buddy box. When the student gets into trouble it gives the instructor the freedom to allow the student to correct the problem. Without a buddy box the instructor has to worry about when to snatch the transmitter from the student's hands. In the excitment some students really latch on.

If you have a second transmitter all you have to buy is a cable to connect the two transmitters. If you only have the one transmitter, your instructor may have a spare you can use. If not, a buddy box is cheap. Well worth the cost.

Eric