I would think as a head you're caught between the devil and the deep blue sea. At the end of the day observations are a means of demonstrating that teaching is what it is in each class. A formal procedure has to be carried out a) to justify it to OFSTED, b) in case any disciplinary procedures need to take place c) as a record of your own professional development. I'd like to think that if and hopefully when the time comes for me to become a head I too would adopt an 'informal' drop in approach to know what teaching is like, because it works both ways, you know what's going on and actually carried out in the right way it can be seen as supportive. The truth is however that informality doesn't stick too well with teacher judgements, prof development and disciplinaries. I was observed this morning and last week Eng and Maths respectively, too be honest I felt like saying at the end of today's obs "I hope you've learnt something from watching me!" but I knew the head was there to tick the box so that she could report back to govs and other interested parties that yes, teaching in my class was at least good. Observation is like so many things in Education, a process, a game, a box we have to tick, admittedly it's an annoying one, stressful too, but it is what it is and I can't see it ever changing. For the record, did I prepare for it for hours? Not really, more than my average lesson, but I taught what I had planned for the week anyway. It wasn't Outstanding, but for me as other posters have quite rightly said, Outstanding lessons every time is something I can't and won't even try to achieve. I'm just proud of being a good teacher and the children do learn something most of the time and in my mind that's job done!