Introduction of diploma work obtains comprehensive inventory of informations from sententional calculus theory, which correspond to problems that are mentioned in examples in diploma work. These teoretical knowledge regarding to needs of work are mainly analysed on secondary mathematics grade, marginally intervene in problems of college logic. Practical part is a task collection for children in infant school and evaluation of their succes in solving examples. I gave chosen examples to children twice. First time at first lesson, where children expresss their opinions to possibilities of problem solution. These opinions weren´t revised. Next time children made the same examples at last lesson after all preparatory exercises. There were seen progress in childrens argumentation close to information about results. Not until this lessons were children acquainted with correct results. In last part of diploma work I mention my experiences and knowlegde about logic for children and some advices for teachers and parents how to work and evolve children´s logic.