I've been scratching my head about this for a while now. I'm the kind of person that takes out unneeded words, and can the 'then' in "and then" be omitted? Here's an example. "Aeria drank from the water fountain, and then went to the classroom." Could it be reduced to "Aeria drank from the water fountain, and went to the classroom." I was wondering if it the 'then' was needed to show something being done in sequence or if the reader already imagines it being done in sequence.
Technically, you need the "and" because "then" isn't a conjunction. It's frequently used like one, though, without the grammar police coming to drag you away. I'd tend to avoid "then" and prefer just "and". Or I'd make it 2 sentences: Aeria drank from the fountain. She went to her class. As long as there are not constantly too many tiny little sentences, it's fine. In any case, the sentences are not so related that you have to join them, and we can grasp the sequencing without "then".
If only we could convince Blackstar that writing well does not mean simply using the fewest possible words ... I mean, is there anything really wrong with using "and then"? Just stick both words in there and carry on. Nobody will bat an eye.
I usually just say "then", but I wouldn't hesitate to say "and then" if it felt necessary for some stylistic purpose. Just depends on what you are saying. How you say it should reflect that.
I've heard that in "and then", the "and" is superfluous, and in my writing, I do sometimes drop it if it feels appropriate (e.g. the sentences flow better without it), but the way I've understood it, it is wrong because "then" is not a conjunction. Surprisingly many critters have recommended me to do away with the "and", though. That has basically led me to do away with "timing" the action with then's, which might actually be a good thing. I do still use "and then" every now and then.
