Had another couple of questions from my friend Jeanette in Iowa, about teaching past tense. I've had these questions from others so I'll go ahead and answer them for all interested.
Transitioning to past tense - here is how it works in my books (more or less following Exprésate's curriculum sequence:)
Past tense is first introduced in the last five lessons of Spanish 1B 2009 Version, in the readings only. I still tell the story in class in present tense, then have students read a version of it in past tense aloud with a partner (reading for me in class = translating it out loud into English so I know if they know what it says.) This is pretty much no big deal for the students; they can easily recognize and read "miró" in context after seeing "mira" a few million times in the course of my Spanish 1A & B 2009 Version. I might have to explain that "fue" means went, but that's about it.
I don't prepare for these past tense readings in Spanish 1B 2009 with any kind of preterit/imperfect lesson; they just get the page of reading, I tell them it's in past tense Spanish and I want to hear them read it in past tense English please, and they read. No big deal. My goal here is that they simply start seeing and recognizing past tense Spanish verbs in context.
As they are getting these past tense readings at the tail end of 1B, I might do a grammar lesson on preterit and/or imperfect if I have time, but not until they've already read a few stories in past tense and had time to notice the change in endings on their own. (I really think I'm wasting my time teaching explicit grammar when they have had no contact with that particular grammar structure already via comprehensible input, but that is just my own opinion.) I haven't taught Spanish 1 in a couple of years, but I know my colleague Alexis didn't quite get to the final 5 lessons and that's fine. We plan for her to pick up where she left off in 1B at the beginning of Spanish 2, which will work just as well for my purposes, which is for them to truly acquire Spanish proficiency in speaking, reading, writing, and listening and not just rush through the material trying to memorize for tests.
Past tense continues of course in Spanish 2A and 2B 2009. The first couple of chapters of Exprésate 2 are a huge review of Spanish 1 (and there are long, long lists of new vocab,) so I wrote the scripts to tell in class as well as the readings in present tense in order to hopefully give students more time to nail down present tense more fully before heading into past tense. Starting after the midterm, the scripts in 2A are in present and the readings are in past, through to the end of the first semester, much like the last few lessons of 1B.
My Spanish 2B 2009 is all in past tense, scripts as well as readings, with the vocab list shortened and simplified so we could focus 100% on getting preterit and imperfect down pat. My 2A stories are actually pretty hard to understand and read vocab-wise, so in 2B I took it down a notch like I said to try to make past tense verbs more of the focus than complicated, endless vocab lists.
My Spanish 3A & B 2012 is all in past tense, scripts and readings, with present tense popping back up mostly in the conversation and class discussion topics and journal writing prompts. I find my students still need plenty of practice in present tense in order to prepare for the AP Spanish Language and Culture exam, and this fall I intend to step that up quite a bit. You can't make a lot of errors in present tense and make a 3 on the AP Spanish exam, because that's considered "frequent errors in elementary structures" (and a 2) on the AP grading rubric. So I say you really can't overteach or overpractice present tense, and I'm happy with how much I kept it going through the end of 2A.
Anyway, that's my method for now!
Anyway, that's my method for now!