Importance of vocab and reading comp

I thought it was a simple prompt for my midterm, which consisted of writing a summary and opinion. The piece was entitled "Don't Eat the Flan." Students were scrambling to decode words like gluttony, therapization, etc. Furthermore, although I thought most had a Catholice background, they did not seem to understand about much about the seven deadly sins.

Additionally, two students who were sitting at the same table said they had come up with totally different understandings of the author's thesis.

It is important to choose a prompt carefully, even if it was from a more basic writing textbook. Students need to understand the importance of vocabulary in reading comprehension. We as instructors need to understand that reading comprehension is another step we must teach before the summary and opinion essay.