Subject: Why do you see lightning and sparks but not other electricity?

I am doing my 1st grade science fair project on electricity.  I can't see the 
electricity that flows through wires--it's kind of invisible.  Why can I see 
the electricity when it is lightning, or when there is a spark?  My project 
will show how electricity lights a light bulb and how static shocks you.  I 
also want to show lightning and why you can see it.  Thank you!

Re: Why do you see lightning and sparks but not other electricity?