I'm with puffin on having options. Each option may offer significant benefits for different kids and their families. Not sure how options would work... teacher A is holding regular class, teacher B is holding flipped class... families choose which option they prefer and make a 1-year commitment?

I'm wondering how this may reflect in research? My hunch is that both groups would perform better than a control group (students in the previous year, students who did not make a choice). An improvement in performance may occur simply because these families made a choice and feel something at stake in making it work. An improvement in performance may also occur because they chose a learning system which best suited their needs, learning style, etc.