Working as a group, design a coordinate system that could uniquely locate the seats in a football stadium. Discuss different ways to choose the zero point of the coordinate system.
Have one member of your group pick a star in the sky and state the altitude and azimuth of that star. See if the other members of the group can locate the chosen star in the sky. Continue with different group members picking altitudes and azimuths until everyone in the group has mastered the horizon system.