Re: How can I make it rain in the classroom?

Not knowing to what scale you would like to do this, let me give you a simple 
demo.  You can do this on several scales depending on the equipment available.

The key to the method is using dry ice or a dry ice ethanol mixture (be very 
careful if you use ethanol due to flammability).  Take a pan of water and place 
it under a metal plate where the dry ice has been placed on top.  The plate can 
be put in a box so the dry ice is hidden.  THe pan of water can be heated if 
needed.  Adjust the metal plate (metal pan if you use the ethanol bath) above 
the water until you show the "rain" developing on the plate, but not freezing 
(if you do it just right, you can get snow!).

It will take some experimentation to see what will work better.  You can put the 
whole thing in a clear box, do it in a hood, or use colored water to show only 
the water that evaporates.  I have even seen a stobe added for lightning.  You 
should always have a hidden metal pan to strike when you talk about thunder.  
Keeps everybody awake.  You can also use one of the mode tapes available of a 
thunderstorm also.

Hope this helps.