Caps lock is a computer lab teacher's nightmare! One reason is it is poor grammar to type in all caps, but another reason is we are using technology in schools so much now, that signing in with a username and password is often required. The #1 reason I see people (students and adults) enter an incorrect username or password is because their caps lock is accidentally on.
I've started something new in computer lab this year. When my students sit down at their computer I ask, "Caps Lock?" And they reply "OFF!" I say "Num Lock?" They say, "ON!" I finish with, "Scroll Lock?" They reply, "OFF!" And then we begin our lesson. This just helps them remember that it is their responsibility to check their work station, sit up straight, face their computer and make sure their keyboard is ready.
Check out this cute reminder video from Good Computer Kids called Typing in ALL CAPS!