I split folk up into groups and asked everyone to put together an essay that was, literally, in pieces. The idea of this was for you to work out the logical sequencing of ideas in the essay and to identify elements like the introduction and conclusion. Of course, some visually astute students noticed that I didn't cut it up very well and achieved this quite quickly by using their jig-saw skills rather than their language analysis skills.
We also chatted briefly about what we mean by an essay. There were some thoughtful suggestions on this: for example: something based on fact; something that has an argument. Does anyone know the origin of the word "essay"? That in itself gives us an idea of what an essay is. And does an essay need to be written?
I also asked you, in groups, to come up with what you regarded as the aspects of a good essay. You did this very well and came up with an excellent set of criteria. These related to the technical aspects of writing (grammar, spelling, punctuality! (or punctuation as I like to call it)); structure; the development of an argument or idea; good introductions and conclusions; strong planning and research.