The aim of the lecture is to present a tool for testing automatic word derivation for Czech. The derivation of some derivational types in Czech is comparatively regular. It can be described by formal rules. A new version of the web interface Deriv working with the morphological analyzer ajka enables us to formulate simple and complex word formation rules and to test them on the material of electronic dictionary of Czech and on corpus. Students can learn from real tasks to descover the word derivation rules for Czech language (data driven learning) .