Chromosomal aneuploidy, a deviation from an exact multiple of an organism's haploid chromosome number, is a difficult concept for students to master. Aneuploidy arising from chromosomal non-disjunction (NDJ) is particularly problematic for students, since it arises in the context of meiosis, itself a challenging subject. Students learning NDJ are forced to actively apply their knowledge of normal meiosis, often revealing previously unapparent deficits in their understanding. Teaching NDJ is thus an important opportunity for students to review and apply their skills in modeling meiosis. This article presents a straightforward method to detect NDJ of the sex chromosomes in "Drosophila" in the context of laboratory exercises to examine recombination of sex-linked loci. It also presents laboratory exercises that allow for detecting maternal and paternal NDJ events within a single cross, an advantage since the use of standard markers obscures paternal NDJ events. An additional advantage of this method is that it easily allows for recombination mapping with recessive alleles "in trans" as well as "in cis". This method allows students to simultaneously investigate recombination and aneuploidy with live organisms, and as such is complementary to theoretical methods of teaching recombination and NDJ. (Contains 7 figures, 1 footnote and 3 tables.)