Summative assessment vs. Formative assessment

I've spent the evening working on my APD assignment. Maybe I'm over-analysing it, or reading too much into the task, but I have not felt so confused for a long time! The more I think about it, the more confused I get. I've tried mind-mapping, brainstorming, paragraph plans etc etc but I seem to be getting nowhere.

Anyway, the point of my post was really to consider how effective this form of assesment is with regard to our PGDE course. Why have we spent so long as potential teachers discussing the benefits of formative assessment in our classroom practice, for me to be sitting writing a summatively assessed essay? Perhaps thats why I'm struggling so much with it. As a learner, I feel so unsupported in this task with regard to what Im doing correctly and the areas I need to improve. I'm not going to go into it... I just thought it was an interesting point. And something which I will remember as a teacher.