Justin Bieber Performs for Students at L.A. School

Justin Bieber's scheduled to begin touring again this summer, but it looks like he's already rehearsing ... to the delight of some lucky kids.

JB held a private mini-concert Thursday for students and teachers at an elementary school in L.A. ... performing a few of his latest songs, including "Holy."

Justin's wife, Hailey, was also in attendance ... it seems this was their fun daytime activity before hitting up the star-studded party in WeHo that night with their old pals Drake and Kendall and Kylie Jenner.

It's appears Biebs' school show was planned in advance for Baby2Baby -- a charity to help children living in poverty -- and the young crowd was definitely lovin' it. Talk about great timing to be back in school!

As we've reported ... Justin's been showing up at some unexpected places lately in L.A., including a visit to the California State Prison to spread the good word.