What Co-Teaching Is; What It Is Not
Some of the essential characteristics of co-teaching include the following:
• Co-teaching is a service delivery option. It is a means through which students with IEPs receive some or all of their specialized instruction and related services in the context of the general education classroom.
• Two or more professionals with equivalent licensure or status are co-teachers, one who is a general educator and one who is a special educator or specialist.
• Both professionals participate fully, although differently, in the instructional process. General educators maintain primary responsibility for the content of the instruction; special educators hold primary responsibility for facilitating the learning process. Instruction employs evidence-based practices and accountable differentiation.
• The students are heterogeneously grouped as a class, and both teachers work with all students. Various combinations of students and group sizes are used, so each student’s educational potential is realized. Co-teachers are firmly committed to “our” students, not “yours” and “mine.”
Just as important as clarifying the characteristics of co-teaching is noting what it is not. It is not a general education classroom with one “real” teacher and one who serves as “the help” or “an extra set of hands.” Nor is it a pullout special education program that has been re-located to the corner of a general education classroom.

Taken from the article, "Is Co-Teaching Effective?", by Marilyn Friend and DeAnna Hurley-Chamberlain