Depending how old they are, you may find charities that will accept them.
Or use them to learn about clustered systems?
For example, a friend of mine had four 4 core, 8GB machines and tried to configure a hortonworks cluster, but the system spent so much time just running the cluster state, that you could only do trivial computing on top of the cluster before the nodes started timing out.
He then spent ages disabling unnecessary services, re configuring components to be more memory efficient - and spent so long doing all of this maintenance he never actually learnt how to compute on top of the cluster, which was his original goal.
So it's best just to pay a few hundred a month to amazon and run your own small cluster that you can spin up and down as you need
Your end user is the 6th grade version of myself. (Curious and interested in computers but no mentors/guidance to get started/lay breadcrumbs). My family/friends came from blue collar background, so their programming skills are effectively zero. Asking for help doesn't really exist since I didn't know anyone to talk to or know where to go on the internet.
When I was much younger (10 years old), a big part that delayed me from getting involved in programming, was not understanding "the point" of programming and figuring what to search for when trying to learn.
I (10 year old version) seriously thought that all programming was: cout << "What is your name?"; cin >> name; cout << "Hi << name; return 0;
Based on the C++ book I had access to, I didn't understand what I could tangibly build from knowing the idea of int,strings,arrays etc. I also thought that when people made games, they hardcoded the raw pixel values for every possible state/character/action. (Dumb, I know.)
I also thought you programmed "cool" games, by throwing a stupid amount of time in hardcoding each pixel value.
So I paused on programming for 10 years and picked up paintball/cars/Mechanical Engineering instead.
Make and install custom Ubuntu image with all of the needed packages/software to do introductory tangible dev work on. Make it work for 3 large dev camps(Python, Web Dev(Basic HTML,CSS,Javascript),Embedded electronics (Arduino). Sure the 10 year old kid can install everything via command line scripts themselves.
But knowing that you need a './" in front of 'script.sh' isn't entirely obvious at that age. It is also incredibly demotivating when your getting your feet wet, and can't figure the './' out.
Have links on the Desktop to the Mozilla Developer Network, Python Docs/ Game Tutorials, the github explore tab, Intro to Python/Web Dev online courses and StackOverflow. As well as a challenge for the 10 year old: Like make a pong-like video game.
The mission statement for this entire idea, "We gave you all the tools and they work well. Now the only thing stopping you from being a hacker/programmer is yourself."
Distributing it via old hardware would be nice, because most kids/parents are worried about "ruining" their existing computer by migrating to Linux and losing Windows.(At least I was)
Having a separate dedicated physical box, will give the kids a good environment to try things and fail in. Without worry about accidentally deleting everything on the file system. Like family vacation photos.
Do FB marketing and target parents that have kids in middle school and want them to go college and be doctor/lawyer/engineer types.
Sell it at (cost + $20 +shipping). Plug and play.
