The setup involved a measuring cylinder full of glycerin; with a pyrex test tube; also full of glycerin; which could be lowered into and lifted out of the cylinder (via a string looped around a bung pushed into the tube).
The Disappearing Test Tube - Group Activity
Grade Level Grades 9-12
Resource Type Handout
A great experiment to use when teaching waves. The worksheet included also raises some good questions for pupils. I especially liked the take on the invisible man!!