A sequence of exercises for the isolation and characterization of invertase (E.C. 3.1.2.26) from baker's yeast obtained from a local grocery store is outlined. Because the enzyme is colorless, the use of colored markers and the sequence of purification steps are designed to "visualize" the process by which a colorless protein is selectively detected and isolated from a mixture of many different proteins. Students then compare their product from each stage of the purification against a commercial standard of purified invertase using both qualitative (SDS-PAGE) and quantitative (specific activity) techniques. The equipment and materials required for this 4-week exercise are either already available in most undergraduate departments or are not cost prohibitive. Our experience suggests that this project is well suited to undergraduate institutions limited to a one-semester course in biochemistry that caters to a large and diverse student enrollment. (Contains 2 tables and 2 figures.)