Depends on the class. I usually have the students make a vocabulary box for each word with the definition, synonym, antonym, picture, and a unique sentence. We act out the words, draw the words, and find nonexamples and examples. I kept a graph on one of my back walls. Basically it went from 1-15. Each time a word was used, talked about, or visually represented, we moved the word up on the wall. Our goal was to move all the words off the wall by the end of the week. This helped me to know which words the students knew easily and which ones I really needed to focus on during the week.
I have a similar issue with my 6th graders. Today I gave them a quiz on simple words (acute, obtuse, angle, etc.), and I was shocked at how many students failed. Keep in mind there were only 12 words and it was matching. I firmly believe that if they can't define a word then they won't know how to use it. This is a replacement position and the original teacher never gave vocab quizzes.