On March 20th, 2014, the Planetarium Science Center at the Library of Alexandria offered high school students Master Classes in Physics. Each Masterclass is a one-day-activity, where researchers invite high school students and let them be scientists for one day. The core activity is a measurement with real data from CERN (Conseil Européen pour la Recherche Nucléaire, or European Council for Nuclear Research). Having performed the measurements, students participate in an international video conference, together with three or four other institutes, according to the schedule, and moderators from CERN. This provides an opportunity for 15- to 19-year old students to discover particle physics. It Takes place in more than 130 places in 28 countries with more than 6000 participants worldwide. They are organized at TU Dresden in the framework of the International Particle Physics Outreach Group (IPPOG).