Students in general undergraduate courses in both biology and genetics seem to have great difficulty mastering the basic concepts of Mendelian Genetics and solving even simple problems. In an attempt to correct this situation, students in both courses at Rollins College were introduced to three simulation models of the genetics of the fruit fly--FLYSIM, MORFLY, and NUFLY. These programs included practice problems on linkage patterns, lethality, phenotype, and genotype. Results of the traditional general biology exam showed that a much higher percentage of students was able to solve the problems than in previous years. Although similar data are not available from the genetics course, the majority of students indicated that they found the computer programs helpful. Student comment in general biology was highly in favor of use of the programs despite the fact that they are very time consuming. (Author/CMV)