Walking Model of the Solar System:

Create a scale model of the Solar System in your school's hallway. I use this in conjunction with Travel Poster to a Planet.

Travel Poster to a Planet:

A group project. The following is from the introduction:
Welcome to the future! Space travel is real and affordable. Your group has been employed by Cassini and Kepler, a major advertising company. Your job is to create a travel poster for a planet in the Solar System. You will need to convince potential tourists that their dream vacation is on your planet.

Using Craters to find the age of a surface
This is adapted from NASA's
Impact Craters: A look at the Past.