Abstract
In the contribution, the validation process of the Czech Lexicon is presented. It was essential to validate the lexicon to ensure that they would be useful both for use within the Czech Republic (and other involved countries) but also in communication with mathematics educators and teachers from abroad.
This validation had to validate both usability and comprehensibility at home and on international level. The three levels of validation are national validation, validation by another lexicon team and bilateral comparison of two lexicons.
The aim of the national validation was to analyse main differences in the language of teachers and researchers, clarity of the used terms and descriptions for teachers and completeness of the list of terms and descriptions. The main aim of the validation by another lexicon tam was to improve the clarity of descriptions of terms so that national lexicons could be used for further comparative activities done by the whole lexicon community.
The aim of the bilateral comparison of two lexicons was to compare different naming systems to describe the events, actions and interactions of the mathematics classroom. The focus of this contribution was on three types used for validation of the Czech lexicon.