I've done many demonstrations in many schools, not as a project because I own my own dojo.
It's a lot of fun, and the schools are very supportive. They have all the equipment, especially if you plan it during a school festival, like here in Houston every school has an international festival.
The school will supply the equipment and Audience.
Here is a link of some photos of a demo I did at an elementry school.
If you have any questions about planning or if you would like some ideas, send me a message and I can send you outlines and notes to what I've done in the past.
I've also got many other groups to participate. In the photos you will see a karate group as well as a ninjutsu group, the theme was martial arts to Japan.