The use of didactic models to illustrate Mendel's crossings is one of the options for working these concepts in a different way. Creating a simulation so that students can analyze how the crossings performed by Mendel in the experiments that were the basis for the First Law happened. The present study proposes the use of a didactic model to aid in the understanding of the basic concepts and crossings of Mendel's First Law in order to create an alternative approach to the expository-dialogical strategies.