Some of the most common close votes are for people who have posted homework questions, to which the usual appropriate response (to my understanding) is to flag as off-topic with the message "MathOverflow is for mathematicians to ask each other questions about their research. See Math.StackExchange to ask general questions in mathematics." However, many of those questions fail to show any work, which leads to the question being inappropriate there as asked. This often leads to comments that are all approximately the same: "This is not appropriate here; you may have better luck on m.se. There, you will have to show your work."
It may be useful to include an option (possibly on selection of the quoted option, possibly on deletion, etc.) to add something like "This looks like an assigned problem; you will have to show your work so far and explain where you are getting stuck" or something similar.