It is a fundamental idea of computer science to search for, define, analyze, and operate with construction kits consisting of small sets of basic building blocks and a small number of operations to combine the building blocks to larger objects. While the construction kit is mostly simple, it often defines a vast, complex field that consists of all possible objects that can be built from the building blocks by using any (finite) sequence of combinations of operators. This idea affects and structures many areas of computer science. We present examples from several fields, including imperative and functional programming languages, computable functions, Turing and register machines, Boolean functions, data types, object-oriented programming, characterisations of formal languages along with examples from other disciplines. How can informatics lessons profit? If lessons are oriented towards a fundamental idea, the idea may explain, structure, and integrate many different informatics subjects and phenomena by a single recurring scheme. On the other hand, the construction kit principle belongs to the sphere of everyday thinking so students already have a basic intuition of the concept which may enhance their understanding when entering any field where the idea applies.

What do the painter Yves Klein, the sculptor Richard Serra, the composer Terry Riley, the techno DJ Paul van Dyk, the Volkswagen cars and any informatician have in common?
They try to get the maximum out of the the minimum, i.e. they wish to create most diverse and complex pictures, sculptures, pieces of music, artworks, collections of car models, or informatics systems out of the smallest possible reservoirs of combinators operating on few colors, shapes, notes, rhythms, car components, or basic informatics objects.
For an informatician it is a fundamental idea of computer science to search for, define, analyze, and operate with construction kits consisting of small sets of basic building blocks and a small number of operations to combine the building blocks to larger objects. While the construction kit is mostly simple, it often defines a vast and very complex field that consists of all possible objects that can be built from the building blocks by using any (finite) sequence of combinations of operators. This idea affects and structures many areas of computer science. We present examples from several fields, among them are

• imperative, functional, and predicative programming languages,
• computable functions,
• Turing and register machines,
• Boolean functions,
• data types,
• VLSI,
• characterizations of formal languages, and
• algorithmic paradigms,
along with examples from other sciences.

How can informatics lessons profit from this observation? On the one hand, if lessons are oriented towards a fundamental idea, the idea may explain, structure, and integrate many different informatics subjects and phenomena by a single recurring scheme. On the other hand, since an idea like the construction kit principle also belongs to the sphere of everyday thinking, students already have a basic intuition of the concept which may enhance their understanding when entering any of the fields where the idea applies.
We conclude with some examples of totally inverse situations, where complicated construction kits appear in everyday life while the fields they define are more or less simple, and shortly discuss possible social consequences.