Fill one graduated cylinder with a thick fluid, and fill another graduated cylinder with a thinner or less viscous liquid. Make sure each cylinder has an equal volume of fluid. Drop a marble into the cylinders simultaneously. Record how long it takes each marble to reach the bottom of the cylinder. The fluid in which the marble moves the slowest is the more viscous fluid.
Fill two burets with equal volumes of two different fluids. Simultaneously open the burets to full flow and catch the fluid in two different beakers. After 10 seconds, simultaneously stop the flow in the burets. Whichever buret loses the most volume is the one containing the less viscous fluid.
Fill two Styrofoam cups with two separate fluids. Poke a hole in the bottom of the first cup with a pencil and record how long it takes for the entirety of the fluid to drain out. Poke a hole in the bottom of cup No. 2 and record how long it takes for the entirety of the fluid to drain out. Whichever fluid takes the longest to drain is the most viscous.
Cover a piece of cardboard in non-stick aluminum foil. Draw a line with a pen horizontally 2 inches from the top of the board. Use a pipet to place one drop of each liquid next to each other on the board as the board is flat on a table. Prop the board up so that it's now perpendicular with the table. Whichever drop of fluid takes the longest to reach the bottom of the board is the most viscous.