Full Question: What do you mean by co/team teaching? Do you mean departmentalization? Or do you mean several teachers teaching at one time? Also, what would be a "good" effect size? Your effect size list has co/team teaching at a 0.19 effect size. Could that be interpreted as poor?
Answer: “In too many cases team teaching, co-teaching, innovative learning environments are poorly implemented hence the low effect size. So often it is not co-team etc., but one teaching after another and never underestimate teachers’ ability to use pot plants, bookcases and filing cabinets to create traditional egg-crate classrooms. When it genuinely is team teaching it is magic. I work with teams in classes of 90+ (from Year 1 upwards) and not only (if planned right) does teachers after school work go down (e.g. in one school with three teachers and 90+ kids, each teacher plans for the other team one of three semesters in a year, which means two out of three semesters there is no planning!!! And I have seen the best teaching – but too often teachers are dumped in open classrooms and expected to know how to use this opportunity” (John Hattie, personal communication, February 24, 2019).