Re: writing in English
While I agree completely with Tdol, if your students are just learning, it may be best to follow the same model at first and to simply lead off your introductory paragraph with a topic sentence to start with.
As their writing becomes more advanced, they can lead off with an attention-getting sentence, and then state their topic sentence at the end of the first paragraph.
I would suggest that burying it in the middle of the paragraph is not a good idea.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.