I have just come across a post on the cover supervisor thread by < headbeck>. Headbeck was covering a practical science lesson and had an incident with a student holding a cigarette lighter to an aerosol can and was seeking help and guidance on the TES forums. So we now have cretinous Heads who put cover supervisors in science labs to 'teach' practical science. This is a national scandal and i have copied < headbeck's post to Gove at the Df E. The Head of this school must be brought to book. Sad and horrifying it would be , but a serious incident is necessary to put an end to the madness of using cover supervisors as cheap labour in our schools. Unemployed teachers will be cringing when they read how Heads are using loopholes and a CRB check to save on staffing budgets.