Summary: In Hungary algorithmical thinking is a part of teaching informatics both in primary and secondary grammar schools. A teacher usually starts with some everyday algorithm, taking examples from cooking or solving a mathematical or physical problem. The steps of the solutions are usually represented in a flow diagram. This diagram is a graphical representation of the algorithm steps including decision symbols. With these decision symbols, selections and iterations can be applied. Unfortunately, the common ways of describing algorithms are far from functional thinking, therefore it is rather difficult for teachers to find materials on teaching functional programming. On the other hand, programming and trying the algorithm in a functional way is much easier as in the imperative way. The next step is usually the description of the algorithm by a sentencelike language, which is very close to BASIC programming language. At this point the teacher switches to a programming language, like Pascal, BASIC, C\#, all of which are imperative languages. These languages were taught to teachers during their studies, and are used in their workplaces, in grammar schools as well. We believe that the functional programming paradigm is raising nowadays, and getting more and more important. In this paper we are trying to show and prove that this programming style is appropriate for teaching programming in grammar schools.