It would be great to allow an option to test out of certain words on vocabulary sets to cut down on the quantity of words for students with some outside experience or practice- by showing the English term and asking for the Spanish (short answer), and if a student knows it, it counts as "known" and goes straight to the review category. I'd recommend doing this before even having the vocab list viewable. I'd have the first option "try pre-test?" or "start lesson" buttons upon starting the module.
In the pre-test, students can either type in an answer, or choose an "I don't know" button to skip it and it put it straight onto the upcoming lessons without having to type it out.