Take a 1 foot square cardboard box and paint the inside black. On opposing sides cut out windows for viewing and cover with some type of clear plastic by taping it on the inside of the box. Cut a hole the size of a paper towel tube in the top of the box and insert 3 tubes taped together, tape them in place so that about 1 inch inside the box, make sure this is airtight. On the non-window sides cut two slits from one inch from the top to one inch from the bottom. Set an electric heating plate to medium, put on an aluminum pot of water and place the box over this. Watch through the windows as the tornado forms.