Experiments 1 and 2 introduce the role of metals in biology through the demonstration of the prevalence of metalloenzyme catalase in potatoes and yeast. Some students correctly predicted that the room temperature potato would react most vigorously creating the most fizz. After the experiment, we discussed how catalase in the potatoes stays properly folded at room temperature and therefore, is most active. This rather simple experiment introduced the concept of protein activity being dependent on temperature and enabled the students to appreciate the relationship between protein structure and its function. The elephant toothpaste reaction was exciting and fun for the students since they were able to choose the color of the reaction and observe the cloud of bubbles vigorously escaping the flask. We discussed how the reaction was caused by the same enzyme that is in yeast (catalase), and how this enzyme is also found in our bodies and uses iron to function.