Wow - you got some really unhelpful responses. That's pretty unusual
for this forum.
My suggestion is a greasemonkey script. I'm assuming here that your
kids are accessing gmail as webmail at the gmail site, and not using a
mail app. You could try a mail app, and set it not to download
anything in the spam folder or the trash folder. But if you still
want to use webmail, look for a greasemonkey script that does what you
want.
I only looked for a few minutes, but I found one that would eliminate
the spam count, which might work very well for you, on an out-of-sight-
out-of-mind basis.
http://userscripts.org/tags/gmail
You might be able to find exactly what you want, though, with more
searching. Good luck!
Chak