Adopta una Estrella is a contest for teams of three students to compete across three categories -- one for astronomical measurement, research and documentation; another for astrophysics observation and/or experimentation; and one last for the planning of a scientific outreach campaign dealing with either topic.
The competition is international, open to all Spanish- and Portuguese-speaking countries, and run in collaboration with CSIC, Spain's national scientific research authority, UNED, Spain's remote learning university, and a number of scientific entities including the Spanish Astronomy Society (SEA).
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There is no fee attached to registering an entry to the Prizes, but some cost can be expected in developing or carrying out the project / activity that is being entered to the Prize.
As this contest evaluates activities led by a teacher, the technical skill on the students' part is unlikely to be high.
Given the little means and space that schools will typically have to take on the subjects of Astronomy and Astrophysics, time commitment is unlikely to exceed 3 hours weekly.
Simple registration form + documentation of project not exceeding 10 pages.