Text entry interaction - return automatically submits the answer?

I'm building a series of "compare your response" type of knowledge checks. The learner can basically enter whatever they want and then hit submit and an "example" answer will be returned, as feedback.

My problem: When the learner types their answer into the box and hits return (to start a new paragraph or line) it automatically submits the answer before they are done.

I want to disable the return key from automatically submitting an answer (so that line spacing can be used for paragraph answers).