The purification of a protein is the essential initial step in the study of its physical and biological properties and is one of the most common procedures in biochemistry. This article describes a method for teaching purification skills through the partial isolation of ferredoxin-NADP+ reductase and ferredoxin from a single cell batch. The method has been used for several years in an introductory biochemistry course using spinach leaves as cellular source. The protocol gives a complete picture of the preparation of a crude extract and the subsequent isolation of both electron transport proteins on a laboratory scale. It introduces students to the use of different techniques for the purification and detection of proteins and allows them to develop a number of valuable experimental and analytical skills without necessarily resorting to complicated or expensive equipment.