It's difficult to hold a meaningful lab on evolution, at least one that we can do in a single afternoon.
Evolution usually extends over several human lifetimes, often over millions of years or more.
One of the ways we can demonstrate the reality of evolution is to simply consider biodiversity , the large numbers of species, many of which may have similar forms, but are reproductively isolated from one another - like lions, tigers, leopards, cheetahs, house cats, lynx, mountain lions, bobcats, and all the other members of the Family Felidae. It is difficult to imagine any process other than evolution that could have produced such an amazing number of ways to be a cat. Organisms who live on different continents, but in similar environments, are often very similar to one another. Animals like the American bison and the African wildebeest, both large mammalian grazers who browse in open grasslands, hint at the broader patterns of evolution. Further evidence of that pattern comes from a detailed study of biogeography , the geographic distribution of plants and animals.