The walking water experiment is a simple classroom project that shows how water can move through tiny spaces in paper towels. Cups of colored water are connected with folded paper towels, and the water slowly travels from one cup to the next. This matters because the same kind of movement helps plants pull water from roots to leaves.
It also lets students see color mixing in a bright, hands-on way.
Key Facts
- Capillary action is the movement of liquid through tiny spaces without needing a pump.
- Water sticks to paper fibers by adhesion and sticks to itself by cohesion.
- The water climbs the paper towel because adhesion and cohesion work together.
- Red + yellow = orange, yellow + blue = green, and blue + red = purple.
- A good setup uses folded paper towels with one end in a colored water cup and the other end in an empty cup.
- Distance traveled can be found with d = rate x time when the speed is steady.
Vocabulary
- Capillary action
- Capillary action is the movement of a liquid through very small spaces, such as the gaps between paper towel fibers.
- Adhesion
- Adhesion is the attraction between different materials, such as water molecules sticking to paper fibers.
- Cohesion
- Cohesion is the attraction between particles of the same substance, such as water molecules sticking to other water molecules.
- Primary colors
- Primary colors are basic colors, such as red, yellow, and blue, that can be mixed to make other colors.
- Mixture
- A mixture is a combination of two or more substances that are physically blended together.
Common Mistakes to Avoid
- Using paper towels that are too short, which is wrong because both ends must reach well into the cups for water to travel across the bridge.
- Filling every cup with colored water, which is wrong because the empty cups are needed to collect water and show new mixed colors clearly.
- Removing the paper towels too soon, which is wrong because capillary action can take several minutes to move enough water for a visible result.
- Using too much food coloring, which is wrong because very dark water can make the mixed colors hard to identify.
Practice Questions
- 1 Six cups are placed in a row. Cups 1, 3, and 5 contain 100 mL of colored water each, and cups 2, 4, and 6 start empty. If 25 mL moves into each empty cup, how much water is in cups 2, 4, and 6 combined?
- 2 Water climbs a paper towel at an average rate of 1.5 cm per minute. How far will it travel in 8 minutes if the rate stays the same?
- 3 In the experiment, why does water move up the paper towel even though gravity pulls it downward?