Beverly Hills, 90210 ... 21 Jump Street ... The Facts of Life ... see where they rank on our list.

The bad news? Summer's almost over and it's nearly time for school again.

The good news? We've got just the thing to ease you into back-to-school mode: Our countdown of TV's 21 best school shows ever.

So sharpen your No. 2 pencil and dive in to see which series just make the grade and which ones are at the top of the class.