I certainly was in the early '90s. I know that PGCE students I've mentored less than a decade ago were told this too. I agree that effective planning will possibly reduce some poor behaviour, but prevent it happening at all? No chance! This has been discussed on Opinion: http://community.tes.co.uk/forums/t/486601.aspx?PageIndex=1 It has been rightly (IMO) dismissed as nonsense. So, can any student teachers comment on this please?