I have always loved rain. I love the sound of rain as it hits the roof. I love the smell of rain, and how it refreshes the air. But most of all, I love the rainbow that comes after the rain. My middle son also loves rainbows, so I wanted to create a simple preschool science experiment he could do with me. A couple of years ago, I made an American flag with my oldest using the properties of water, and I decided the same method would be great to create a rainbow!
When my son and I made the American flag, we cut separate strips of paper to create the red strips and blue rectangle. But since a rainbow is the color spectrum of light, we could use the primary colors (red, yellow, blue) to make the other colors of the rainbow (orange, green, indigo). All we needed to do was allow the primary colors to blend with each other!
Rainbow Properties of Water Experiment
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Step 1: Fill each jar with water.
Step 2: Pour 10 drops of red in one jar of water, 10 drops of yellow in another jar of water, 10 drops of blue in another jar of water, and 5 drops of blue and 5 drops of red in the last jar of water.
Step 3: Measure the paper towel lengthwise, and draw six (6) evenly spaced vertical lines.
Step 4: Draw down each line using the wax stick or white crayon.
Step 5: Cut a quarter of the way down each line from step 4. Bend back the second, fourth, and sixth sections.
Step 6: Place the jars of water from step 2 on a baking sheet.
Step 7: At the same time, place the first section of the paper towel into the red colored water jar, the third section into the yellow water, the fifth section into the blue water, and the seventh section into the purple water.
Step 8th: Watch as the water travels down the paper towel.
Step 9: Once the water has traveled all the way down, remove the paper towel from the jars. Lay the paper towel flat on the cookie sheet to dry.
Step 10: Once dry, you’ll have a beautiful rainbow, just like the ones after a rain!
Printable of American Flag Experiment
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Which Property of Water is being used?
As I explained in our experiment when we made an American Flag, this experiment shows capillary action in action! The water travels through the paper towel for two reasons. First, all paper is made of a sugar molecule call cellulose. Water is highly attracted to cellulose and wants to bond (or stick) to it. Second, the cellulose fibers in a paper towel are made with spaces between them. Since water likes to stick together, the water fills these spaces as it follows the water attracted to the cellulose. More spaces allow more water to be absorbed.
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