This module aims at introducing the essentials of linguistic structure through the discovery of regularities in actual data from various languages in the same way it is required at International Linguistic Olympiads. In the first part of the module, students will solve actual puzzles, i.e., problems that can be settled solely on the basis of a carefully selected array of data. In the second part, they will have to gather and evaluate data themselves, and extract regularities from them. The aim is to cover the most basic types of problem that arise in connection with the phonology, morphology, syntax and semantics of human languages without introducing heavy theoretical machinery. However, the students will get acquainted with elementary linguistic concepts in all these fields.