Have you ever seen water “walk” up a paper towel and mix colors along the way? The Walking Rainbow experiment is a fun and engaging activity that allows students to explore capillary action and diffusion while creating a visually stunning rainbow. This simple experiment uses cups, colored water, and paper towels to demonstrate how liquids move and interact.

Capillary Action in Action
Capillary action occurs when liquid travels through narrow spaces, even against gravity, due to adhesive forces. In this experiment, paper towels act as pathways for the colored water. As the water moves upward, it carries the pigments along, forming the walking rainbow effect.

Diffusion: Mixing Molecules Naturally
When the colored water reaches the next cup, diffusion occurs—molecules move from areas of high concentration to low concentration. This blending of colors produces secondary colors, such as orange (red + yellow) and green (yellow + blue). Students can observe how molecules naturally spread and mix in real time.

Learning Beyond the Colors
This activity teaches more than just color mixing. Students gain insight into properties of liquids, solubility, concentration, and molecular movement. It’s a hands-on way to connect scientific concepts to everyday phenomena.

Why It Matters
The Walking Rainbow experiment encourages curiosity, observation, and inquiry-based learning. By watching liquids travel and colors combine, students experience science in action, making abstract principles tangible and memorable.

References:

1. Fetter, C. W. (1999). Contaminant Hydrogeology. CRC Press.

2. Krajcik, J. S., & Czerniak, C. M. (2013). Teaching Science through Inquiry. Routledge.

3. Novak, J. D. (2002). Meaningful Learning: The Essential Component of a Successful Science Education Program. In Learning Science: The Science of Learning (pp. 1-12).