Can you turn the sound off for Siri on the iPhone 4s?

I have the iPhone 4s and when I'm in class it makes noise and I get in trouble. Can I turn the sound off for Siri? I've only been in school for about 12 days and I have already have gotten 3 detentions.

Here's an idea. Try paying attention in class instead of screwing around on the phone, unless you expect everyone else to actually do your work for you later in life.

We'll that escalated quickly…