How can you explain to me the Preterite tense?

The Preterite tense is used to describe completed actions, which are usually accompanied with a time frame. For example, Last week, I ATE a sandwich; 2 years go, I WENT on holiday. I would make comparisons with the other past tenses with which the students may be confused and get to the root of any misunderstanding. I would proceed to give the student a series of questions to complete and then ask the student to explain to me what the differences are after having corrected them so that they can prove to me that they also understand. I would then set more questions as homework or give them a written task where they would include the usage of this tense.