This laboratory experiment is designed to allow undergraduate students to gain experience in polymer synthesis and characterization. Polystyrene quantitatively end-labeled with fluorene is produced via atom transfer radical polymerization run under a nitrogen atmosphere, using unpurified reagents and solvents. Molecular weight characterization of the polymers is performed using UV–vis spectroscopy, eliminating the need for specialized equipment such as gel permeation chromatography. Number average molecular weight values are obtained using Beer–Lambert's law, which is used to determine the molarity of fluorene-labeled polymers in THF solutions. These calculated values consistently agreed within 11% of molecular weights obtained using calibrated gel permeation chromatography systems, demonstrating the accuracy of the results. This laboratory exercise is suitable for undergraduate students in an organic or polymer chemistry course and requires no previous experience in polymer synthesis or characterization.