Getting rid of Gmail spam automatically

I've just got my 9-year old daughter on Gmail. Naturally, she asked me what are those mails in the Spam folder. I told her to ignore them as they are junk mail.

Tried looking for ways to hide the spam folder or force immediate deletion of mails in that folder. There's no way to hide the folder, but here's a nice tip to delete those spam messages automatically. It works and it's cool.

Have fun:)