Or you may find the children are not used to going outside at night, and need some coaxing and assistance to make worthwhile observations. If you have a genuine interest and it shows, then you are halfway there. Add a telescope, as large as is practicable. They are not easy to use, so practice days before the event. Quality is important.
Posters are great teaching tools - eg spaceflight, solar system, star fields, galaxies, nebulae.
3-D models are essential for modelling the Earth Moon and Sun. Add a set of slides of the night sky and some of the objects in it, shown in a DARK room. Pipehenge is a great tool. It provides a frame of reference with which to visualise the patterns of movement in the sky. I use both portable and in-ground versions all the time.