This paper introduces the use of the Internet for educative goals as web applications. In our opinion, the web can have many advantages over other means of teaching, mainly because it can include most of their features. Our work consists in designing and implementing a tutorial system that can be easily accessible through a Net browser. It is for that purpose that we designed MEDAL (MEndelian traits Deduction ALgorithm), a partially interactive tutorial system that is aimed at increasing the understanding of genetics. As an interactive example, MEDAL uses Mendel's laws of genetics for dominant and recessive gene expression in hereditary transmission. It is capable of deducing the genotype of the user and his' parents. With the same principles applied, MEDAL interactive example can deduce to a certain extend what the kids of the user would look like. The MEDAL system tests the knowledge level of the users before and after the tutorial on general genetic laws, to help them keep track of their progress. MEDAL uses interactive examples to do part of the teaching. This feature allows someone to deduce his or her own genotype and deduce, to a certain extent, what this person's children would look like. Even though MEDAL was intended to be an educative tool, it shows some of the future possibilities of merging computers and genetics.