Scientists sort living things into groups based on how they are related — a classification system called taxonomy. You visit a zoo, botanical garden, or nursery and pick three species that interest you. For each one, record both the common and scientific name. Then research the full taxonomy: kingdom, phylum, class, order, family, and genus. When you compare the rankings side by side, the level where two species first share the same group shows how closely they are related. Two very different animals may still share a common ancestor — which ones have more in common than they look is often the real surprise.