At my school (technical/trade) we have to do a mixture of lecture and demonstration. I also add problem solving, power point, transparencies. My question to you all is this... when the students begin practicing their lab work with each other, I often loose control of them and they are talking, chit chatting and laughing. I know there is a balance there, because i want it to be an enjoyable experience for them, but I worrry it gets too casual of an environment? Any suggestions on how to control this without constantly saying "SShhh, you should all be working without much chatting?"