Would this sentence be imperfect or preterite?
"Today (in class), we had to talk about our parents"
Would this sentence be "Hoy, teníamos que hablar de nuestros padres" or "Hoy, tuvimos que hablar de nuestros padres"? I think that it would be preterite because that action hasn't happened before, and only happened on that day. It also wasn't a repetitive action and it's not like "we used to have to talk about our parents". I think that I recall hearing it when speaking with a Spanish friend, and the only way that I can think of it working would be "We were having to speak about our parents", which in English is a bit weird. If it is actually imperfect, can somebody explain to me why?! Thanks
2 Answers
Since there is no description going on here, just the fact that you had to talk to your parents, the preterite would be correct.
"We were having to speak, etc." is a rather strange construction in English for which there is no Spanish equivalent. Spanish has a rather large complicated verb system, but it is logical and doesn't do down any weird alleys.
As to the name of the tense in English, I would call it a present/imperfect perfect progressive.
I'm a Spanish speaker who knows English. To get an English scholar's perspective on it i would call on Moderator ian-hill. He's the one I go to for advice on English.

That it hasn´t happened before does´t make any difference, but you are right that it must be preterite. It´s a simple past action that took place in one day.