Educational content was already a thing well before the internet got everywhere.

When I was in primary school, one of the things teachers had us do was debate the pros- and cons- of television. The pro side included educational content.

First Windows PC at any of my schools had Encarta.

Wikipedia can be downloaded in entirety and read offline, though it is so broad it may need a degree of filtering to become age-appropriate even for 16 year olds.