Experiment that proves matter exist in a gas, liquid, or solid?

I need an experiment that proves matter exist in a gas, liquid, or solid. Can some one help me?

Water, ice,normal and steam

magnify the element 665345645x

You might want to clarify what you actually need to prove. It's pretty obvious that matter exists in at least one of those...

that was what my science told us to do.

that was all that my science told us to do.

I'm sure they gave you more than a vague one-sentence description...

this is what told use If you were responsible to create an experiment to prove that matter existed in a gas, liquid, or solid (pick one) what type of experiment would you do? (You cannot write about a Water experiment)

Do a search on the web (http://www.google.com) for Science Fair experiments to get ideas. You can also use http://www.youtube.com to find experiments that prove that matter exists in one of the states above. You still have to write out how the experiment was done and what you learned from it.