The most prominent I know of are quant.ly and forlue.com There was also nickb's New Mogul, but that's dead. There was also another education HN clone by the person behind BrainRacer, but that's also dead.
Do you know why they die out so quickly? Is it just because they didn't generate enough interest? It doesn't seem like it'd be costly or time-intensive to maintain.
BrainRacer's edu news site was shut down due to a lack of traction mainly, but it would probably be best to actually ask the founder as to why exactly.
Fwiw, I also ran a short-lived HN clone for a few months (also for education news) but killed it; mainly because of a lack of traction, and I didn't care too much to keep it up. Only about 15 registered users were on it, and only 4 active submitters, including myself.