The idea of marking with different coloured pens is not new. I have never come across any research evidence to suggest that kids suffer a devastating loss of self-esteem when theysee red scribbles all over their work -- as opposed to green scribbles.
Marking with coloured pens, so-called "deep marking" and recording every instance of formative assessment all combine to make the teacher's workload intolerable.
In this video I talk about the lunacy of marking with different coloured pens. In the bit that is difficult to hear what I said was "the Department for Education" (I was recording this outside, ie it was an open air rant, I mean broadcast). The report referred to is Reducing teacher workload: Marking Policy Review Group report.
I have also blogged about this in the article entitled My 10 point marking strategy, which is featured in the April issue of Digital Education. (Please note: at the time of writing, this has not yet been published.)