I have found that students of all ages quickly become interested in celestial navigation, as it provides a concrete link between the heavens and themselves, one that fills some of them with awe and amazement. It is a subject about which most of them know nothing at all, so it has the added attraction of novelty.
Older students can learn to use the sextant.
And even most adults have an extremely limited understanding of astronomical or navigational metaphors, so whole new worlds open up to them once the original use behind the metaphor is grasped. It always amazes me how little most students know about the sky - usually they can identify the Big Dipper and Orion but little else. Highly, highly recommended for anyone of any age. See also the Navigational Instruments page and the Navigational Astronomy page for further resources. There are a number of graphics which take time to load - they're worth waiting for.