"My idea would be to work on the theory, so you could put that into practice when you're giving a presentation. But your colleague told me that she'd prefer me to give you the handouts of the vocabulary and expressions to use in a presentation. That way, you could each work them outside the class, and come up with your own presentations."
One problem with your sentence is that you say "My aim is ...", that is, you know the colleague wants something different, but you still have the same aim. Or do you?
"My aim was ..." fixes that. Using "My aim would be to ..." is another solution that doesn't commit you either way.
It sounds like a casual conversational paragraph, so your sentences are probably too long, especially the second. People don't normally talk in such long sentences; they may be alright in writing.