This article describes a discovery-oriented experiment for demonstrating the selectivity of two epoxidation reactions. Peroxy acids and alkaline H[subscript 2]O[subscript 2] are two commonly used reagents for alkene epoxidation. The former react preferentially with electron-rich alkenes while the latter works better with alpha,beta-unsaturated carbonyl compounds. The selectivity of these two reagents on carvone, a naturally occurring compound that contains both types of C=C bonds, was investigated. The product mixtures obtained from the two different reactions were analyzed by thin-layer chromatography and [superscript 1]H NMR spectroscopy. Both of the reactions were found to be regiospecific. The selectivity was attributed to the roles played by the alkene C=C bonds, which act as a nucleophile in the peroxy acid epoxidation but as an electrophile in the alkaline H[subscript 2]O[subscript 2] reaction. The discovery-oriented approach is aimed at strengthening students' knowledge of the relationship between the reaction selectivity and the mechanisms. (Contains 5 schemes, 5 figures, and 4 notes.)