Let’s hear it for videogames!
Videogames are enjoyable precisely because they offer a safe environment in which one learns. The learning may not be about the precise dates of battles of the Civil War, but it is arguably learning.
A book I often cite on the matter is called What Video Games Have to Teach Us About Learning and Literacy by James Paul Gee. Gee is a linguist who started to play video games somewhere past his forties. He brings his knowledge of learning to games from an adult teaching perspective.