After reviewing preterite versus imperfect in Spanish 2 or 3, at the end of the unit as a fun practice, I give them fun grammar listening activities to practice the concept covered.
With this worksheet, I have them fill in the worksheet with EITHER the correct preterite or imperfect conjugation. Remind them that preterite conjugations are a one time specific action in the past, and that imperfect conjugations are a repeated action in the past. I have an acronym that I use for the other describing uses of the imperfect, WATERLOADS, that aids them in deciding between preterite and/or imperfect.
I will have my grammar concept manipulatives up soon! Thank you for the interest!