Today we explored why carbon is the "element of life" and identified the four carbon-based molecules that all life is made of: carbohydrates, lipids, proteins, and nucleic acids. We focused our attention on simple and complex carbohydrates, conducting an experiment with dialysis tubing to compare the sizes of two carbohydrates, glucose and starch. We observed yeast using glucose, a simple sugar, as an energy source. With the help of a microscope, we also observed rigid plant structures made of cellulose, a complex carbohydrate.