What is the difference between a high-impact problem and a low-impact problem?
I think "impact" is being used here to mean "effect" or "result" or "influence."
http://www.vocabulary.com/dictionary/effect
Read carefully; look up "result" and "influence" to get a more complete idea of these meanings.
(The primary meaning of the word "impact" has to do with something physically hitting something else, so I hope that's not the meaning you're working with!
http://www.vocabulary.com/dictionary/impact )
A problem that has a high effect on a person or a family is a major problem.
A problem that has a low effect on a person or a family is a minor problem.
How will you now define those terms for your class?