Is there a difference between lavora alla and lavora sulla? This sentence uses alla, but another one in this lesson uses sulla.
I feel like "sulla" is better than "alla", but I don't know why.
surely 'dissertation' is another word for thesis
Yes. There is another Italian word, "dissertazione" that usually means "oral presentation," but the academic usage is "tesi." Report it.
In the slow audio, the lady clearly says "al", not "alla".
You're wrong actually; cause she says that too fast to easily understand.But unfortunately we can do nothing about fast Italian :-|