The international Bebras challenge on informatics and computational thinking is well-known in over fifty countries as an informal school activity. Running the contest annually for more than ten years, we have noticed that the students (and their teachers) consider the activities as a very exciting learning experience in problem solving and increased understanding of what lies beyond ICT. The crucial point of the challenge is the tasks: they focus mainly on the informatics (computer science) concepts and help in understanding beyond technology, they are short, attractive, and answerable in a few minutes; some of them have multiple-choice answers or are open-ended, and others have interactive components (solving by dragging, clicking, sorting, etc.). The performance of the Bebras challenge in many countries during the last years has shown a high acceptance by school students at all levels. The challenge also involves a fairly high number of female participants.