Fill a clear bottle or jar about 3/4 full with water
Add vegetable oil until the bottle is nearly full, leaving some space at the top
Add several drops of food coloring
Break an effervescent tablet into pieces
Drop one piece into the bottle
Watch the bubbles rise and fall
Add more tablet pieces as the bubbling slows
Seal the bottle only after the reaction is completely finished if you want to store it
Use a flashlight or lamp underneath for a stronger effect