Three-part workshop for a group of highschool students interested in physics, astronomy and space science. Topic: Transiting extrasolar planets and exomoons. 1) overview of various detection methods, 2) practical / laboratory in-class demonstration of a transiting exoplanet and moon using a photometer and 3) mathematical derivation of the relationship between transit depth, radius of planet and radius of the host star. This activity is funded by Villum Fonden.