One of my favorite activities using the preterite and imperfect!!!
First, students draw a multitude of injuries that happened to their patient by drawing on the outline of the person (I included an example drawing). Second, they then write true/false questions about their patient (Ex: Did Jorge break his arm?). You can have students exchange papers at this point and answer the T/F questions. Also, you could use the drawings and T/F questions as a quiz or review activity.
Finally, they write a story explaining what happened to the patient.
This allows the students to be creative while incorporating the vocabulary related to accidents.