Came to the comments to make nearly the exact same remark. I, too, remember seeing these in middle school in the 90s, as well as high school. Though, they weren

Came to the comments to make nearly the exact same remark. I, too, remember seeing these in middle school in the 90s, as well as high school. Though, they weren't in my textbooks - but were in the supplemental "educational magazines" that the science teachers would supplement their coursework with, and "Popular Science" magazines that the school had in the library.