You need to be licensed to teach in public schools. In all states, getting licensed requires you to have at least a bachelor's degree as well as a certain amount of supervised practice-teaching experience. Most states require that you have a master's degree as well.

As part of their licensure processes, many states require you to take an exam such as the Praxis series. The Praxis II exam tests your knowledge of the specific subject you want to teach - in this case, special education. The Praxis III exam tests your knowledge of general education theories and teaching methodologies. Passing these tests helps show your competency to teach.