One of the worst cosmetic disasters that can befall a kid, especially in elementary and middle school. They're big, thick as the bottom of a Coke bottle, and make you look like you have bug eyes. They can also earmark you as being a nerd.
Happily, plastic technology has gotten good enough over the years that the lenses no longer have to be really thick. In fact, most cheap glasses (like the kind Lenscrafters makes) aren't even available with glass anymore.