International Particle Physics Masterclasses (MC) is a successful event for high school students. MC has 3 key elements: lectures, execises with real data from CERN and videoconference.
Astronomy Masterclass (AM) in Slovakia was a test if this MC format could work in a different field. The topic of 2006 Astronomy Masterclass was Asteroids, their trajectories and possible threat to Earth. 30 students participated, all from one average class of a high school in Preov. Program included lectures and hands-on data from NASA. It did not include videoconference at the end of AM (there were no other participants to join with)
Instead, it included project competition on astronomy topics 6 projects were handed-in and defended 2 months after AM. AM was very well received by the students. The organizers felt the same enthusiasm on the side of students as during MC.