Tina and Kylie saw an ad on television comparing different brands of paper towels. They decided to run their own experiment to see
which towel could absorb the most liquid. They took several brands
of paper towels and cut them into equal sized strips. They put the
strips in small containers. Next they poured water into each
container. After 2 minutes, they pulled the strips out and measured
how much water was left. What was one variable they forgot to
control?