Preparation of laboratory-scale polyurethane foams is described with formulations that are easy to implement in experiments for undergraduate students. Particular attention is given to formulation aspects that are based on the main chemical reactions occurring in polyurethane production. This allows students to develop alternative formulations to the ones given in the experimental procedure. Chemicals and methods used in the experiment are similar to those used in the polyurethane industry, so students gain insight about the chemistry involved in polyurethane foam production. Foam characterization by apparent bulk density is also described and an example of the expected results is given. Additional characterization experiments are suggested with some alternative foam formulations. (Contains 1 figure and 1 table.)