Have a feeling you are primary. In my secondary game, the agency is giving good advice. I call it a flagship lesson in my subject. A lesson I know works well. In my subject and if the work left is seriously sketchy of the design a poster school of cover thought (the pitts) then I may diplomatically (I mean very diplomatically and only if the opportunity arises suggest something different) You are also correct to think about stepping on teachers toes. As a supply teacher you follow the instructions left by the class teacher as best you can.