Quarantine class got a whole lot better for some 1st graders in Georgia this week ... 'cause Shaquille O'Neal popped in their video lesson to say hi -- and everyone freaked out!!
TMZ Sports has learned the Big Diesel is a family friend of a student at East Lake Elementary in McDonough, GA ... and with the kids in isolation over coronavirus fears, Shaq decided to brighten their day.
The students were doing a lesson over FaceTime ... when O'Neal shockingly popped up on the screen.
The NBA legend said hello to the teacher -- who said, stunned, "Is that Shaq?!" -- and kids and parents on the call all began losing their minds.
You can see in the clip ... dads, moms and students all grabbed their phones to snap video -- all with priceless looks on their faces!!
We're told Shaq stayed on for a few minutes ... saying hi to everyone in the chat -- with one parent telling us, "It was really cool."
It's an awesome gesture from Shaq -- because some kids are struggling with the effects of school closures and quarantines all over the country.
In fact, we're told one of the parents on the group call is doing his best to help provide meals to those in need ... asking for Shaq-like help with the Georgia charity group Operation Lunchbox.