Encouraging young people to actively participate in science is a longstanding and important priority at DESY. To provide high-school students with an opportunity to learn more about astroparticle physics, a number of simple experiments were developed at the DESY Zeuthen campus. Data from these experiments are published on the Cosmic@Web learning platform, along with a range of online analysis tools and introductory material. In addition to local experiments, data are provided from a global network of continuously-operating cosmic particle experiments. Diverse sites participate in this network, including the pole-to-pole research vessel Polarstern, the Antarctic Neumayer III station, as well as the high altitude research stations in Aragats, Armenia and Moussala, Bulgaria. Using Cosmic@Web, students without direct access to an experiment can analyse data in a classroom or at home. The learning platform can also be used to participate in the annual International Cosmic Day. With Cosmic@Web, students can work like real scientists and do their own astroparticle physics research. These developments form part of the German outreach network Netzwerk Teilchenwelt.