A mental image

Mandy says:  “When I’m trying to decide whether I need the imperfect or the preterite in the past and it’s something with simultaneous actions or an interrupting action, I often make a mental image in my head.” First , she draws a horizontal line to represent “the ongoing activity,” or the action that would be expressed in the imperfect (i.e., “If I’m driving down the road.”)   Then, she crosses the horizontal line with a vertical line, representing an action that “comes down and breaks that [ongoing] activity up – it separates it, interrupts it. That would be my preterite because it’s not ongoing.  It’s a one-time thing and it’s done and it’s over.  … That’s my interrupter; that’s the preterite.” Listen to Mandy explain this strategy and give an example in the video clip.