Looks like there are basically 2 to 4 options depending upon if they have all the old computers (& I get them home) or just the "newest" one, which will be about 10-15 years old

1. #Q4OS - https://www.q4os.org/downloads1.html
Good team, many instructions that look easy to follow & probably the easiest to navigate website of the 3

2. #SlackwareOS - good team, many instructions & an active community, but I'm not sure how customized I really need this thing to be & their website is really confusing in its layout
http://slackbook.org/beta/#intro_comparisons

http://www.slackware.com/

3. #Besgnu - single very dedicated person, might help anything I find run including older computers than are my main goal to find & might collapse from the pressures of doing it all themselves. Beyond which I'd have to fish for programs mostly on my own it seems so???
https://besgnulinux.blogspot.com/p/about.html

& possibly

3. #PsychoOS

4. #VoidOS - might use this for a server management