a lot depends on how hydrated the people stay on a regular basis.

dehydration and physical training don't mix so it's probably a good idea to not guess if a student has consumed enough water during the day.

I wouldn't give a kid's 30 minute class a break i don't think...possibly one right after the warmup but that's it...

in an hour long class (kids or adults) I usually give 2 water breaks...but just long enough for them to get 4-6 ounces of water at each break...that's usually enough for a moderately strenuous class. During our 2 hour san shou class I let them drink as they wish between rounds or sets of exercises.

and all the above instances I advocate water only...but, anyone over 18 is an adult and can make their own choices.

Gatorade is drank incorrectly and at inappropriate times by most people. Most people aren't training hard enough or long enough to warrant it. And, even then, watering it down 50% is a good idea.