What is you hope to accomplish - to solicit volunteers specifically for the PTO or to generally encourage parent involvement.
Our middle school PTO is a pretty small organization. We recognize that parents are going to get involved in targeted areas - band boosters, sports, etc.; that there are LOTS of fundraisers; and that the PTO is no longer the central parent organization. (Perhaps in your school it is - but in ours it plays a more minor role.)
The kids are getting older and more self-sufficient. The parents won't interact the same way they did in elementary. On the other hand, you have a group of newbie middle school parents who may still be eager to help. And you definitely want to encourage that.
So my advice would be to think through what it is you want to accomplish and how you can be of service to them. Be realistic when you talk to them, but offer some possibilities.
Does anyone have advice for a new PTO President on speaking before incoming 6th grader parents? Our PTO needs volunteers badly, but I don't want to use the same approach as I hear every year - we do this, this, and this, and we need your help, etc... - any ideas or speeches that have worked?