The nitration of six benzene derivatives having a range of substituents that differ in electronic effects were followed by GC-MS analyses of the crude reaction mixtures and adapted for the second-year organic laboratory. Students pool their results and identify the products by analyzing the mass spectral data of the isomers and by comparing them to the GC-MS analysis of authentic samples. Students determine which substituents predominantly direct nitration to the ortho- or para- and to the meta positions. This simple discovery-oriented experiment illustrates and reinforces the lecture material and provides students with first-hand knowledge of how textbook conclusions are determined in a laboratory situation. (Contains 1 figure, 1 table and 4 notes.)