How are you? No...seriously!

Sometimes, when I ask my students,

How are you?

....they laugh! 

"How are you?" is a normal question! It's not funny. Foreign people ask this ALL the time. I ask my mom almost everyday on Skype. I ask my co-workers and students. Some people say "How's iｔ going?" "What's up?" or "How have you been?" but basically they express the same thing. It's a VERY common question. You cannot ignore it.  (And just because it's a group lesson, doesn't make it okay to ignore the teacher and expect someone else to answer!)

And sometimes this happens:
me: How are you?
student: Haha! How are you?

Seriously- you need to answer the question!
Here are some possible answers to "How are you?"

*I'm fine.
*I'm good, thanks. How are you?
*I'm great! I had a good weekend.
*Not bad, thanks. 
*I'm okay.
*I'm tired.
*I'm not so good.
*Terrible. I had a bad day at work.