Could someone please explain the differences between an expository and a persuasive essay for context.
Theoretically, an expository essay simply
exposes different facets and interpretations of the prompt, whereas the persuasive piece's priority is convincing the audience of a certain contention.
That doesn't mean a persuasive piece doesn't consider the question in different ways, or that an expository piece doesn't have a clear contention. The line between the two styles is sometimes blurry, and you'll probably be writing some sort of hybrid (/combination) style piece.
Practically speaking, expository pieces are
usually in a standard essay format, and persuasives are
usually speeches/ news articles etc.
The difference in content and approach is quite minor, if it's even present at all.
One of my teachers had suggested that we all do persuasive because they were 'easier'. My preferred way is speeches.
If your teacher this year is the one marking your SAC and s/he "suggests" you write persuasively, then that's definitely what you should do. Even though speeches are almost automatically persuasive if you're writing them in Context, it pays to be aware of the advantages of other styles as well
(eg. in expository, you can zoom in, out, and around other examples, integrating all sorts of evidence into the discussion. Creative/Imaginative/Reflectives can also bring a fresher, more engaging perspective. You could combine either or both of these two with the persuasive style and write a hybrid essay - if your teacher is okay with it, of course)