With this, students have to decide whether each verb is conjugated in the preterite or the imperfect. Then, they have to actually conjugate verbs in the indicated tense. The two sides are the exact same questions, but one side is labeled as practice and the other as a quiz. You can either copy all just one side or use the practice side one day and the quiz side the next. Either way, keys are included.
This worksheet/quiz (& key) is part of my Like Water for Chocolate/Preterite and Imperfect Unit. That whole unit is also for sale and includes: vocab list & key, story excerpt with numbered verbs, English/Spanish side-by-side version of the story, comprehension worksheet & key, preterite vs. imperfect worksheet & key, 33 verbs list for identifying preterite vs. imperfect & key, preterite vs. imperfect practice and/or quiz with keys, bingo list with numbers for calling & boards for playing.
You can purchase the whole unit here: http://www.teacherspayteachers.com/Product/Like-Water-for-Chocolate-Como-Agua-Para-Choc-Spanish-Preterite-Imperfect-Unit-1431605