"Thinking outside the lunch box."  It's a term I wished I'd coined but my boss (Dylan Thomas, Public Relations Director for Orange County Public Schools) actually gets the credit there. 

When you want to gain reach inside a school district that's exactly what you should do... reach inside the school district.  It's important that the product, service, or brand that you are trying to promote to that audience - be it teachers, students, or parents - somehow relates and, more importantly, adds to something relevant to them. 

If you have a cleaning product, find places that need to be cleaned and clean them.  Wrestling mats, desks, lockers, parking lots.  Obviously go through the proper channels, just don't show up and start taking graffetti down off walls but that's the general point.  Schools are real estate, curbside appeal is just as huge for a school as it is a home and they are great focal points in the community - what better way to say you are part of the community than to showcase your product, service, brand or team by getting involved in sprucing up the front of a school.

If you have serve a great dish - get it in front of them - there's hundreds of events in every school district across America that would love free food.  Free food attracts more people to events which general is very attractive to a program since they want to inform or educate an audience when holding an event.  Plus, most of the time a school district can't pay for food.  If Science teachers come at night for a quarterly meeting to discuss strategy and curriculum direction and approach, grab a partner (like Orange County Public Schools did with Kennedy Space Center Visitors Complex) and create a "Science Dinner & Experiment" event.  The attendance for the event will soar and your company will look great to this audience since they relate to you and see your support.  Plus, they get to taste your food.

There are hundreds of examples to use but the important message is this:  Be relevant.  Integrate your program.  If you want to reach the audience at schools, reach out to the audience at schools.  Learn what they are doing and find out where you can help.  Sure dollars always help but you can create stronger bonds if you couple that a program that can help your company tie-in to what they are trying to accomplish.