This forensic chemistry activity utilizes presumptive forensic testing procedures and laboratory chemicals that produce screening results similar to controlled substances. For obvious reasons, obtaining heavily regulated controlled substances to create an undergraduate student activity is not practical for most educational institutions. We were able to identify over-the-counter and laboratory chemicals that mimic actual street drugs in terms of physical properties and color response. Using these selected chemicals, the screening aspect of drug testing provides students with the opportunity to understand what obstacles a forensic chemist faces when analyzing a sample of unknown identity. Chemical spot tests (CSTs) and thin-layer chromatography (TLC) were chosen owing to their simplicity, versatility, common use by forensic chemists, availability, and cost of the reagents and equipment needed. Students are expected to explain how simple color reactions can screen for illicit drugs, to describe how TLC can be used to separate and tentatively identify drugs, to predict how polarity changes affect TLC results, and to explain why CSTs and TLC serve for screening purposes only. (Contains 1 table, 1 figure and 1 note.)