Trying make the solar system fit into a tight spot? Got an old tennis ball you want to use to show the scale the sun? Got a computer and no elbow room? These resources should help:
Build a Solar System (Grades: 5-8, 9-12)
This resource from the Exploratorium allows teachers and students to select a size for an object to represent the Sun and all other sizes and distances in the solar system and distances to other interesting stars are calculated. The resource can be very good for a differentiated classroom to reduce the math requirement.
Eyes on the Solar System (Grades: 5-8, 9-12)
"Eyes on the Solar System" is a 3-D environment full of real NASA mission data. Explore the cosmos from your computer. Hop on an asteroid. Fly with NASA's Voyager 2 spacecraft. See the entire solar system moving in real time. It's up to you. You control space and time.