Backyard Paper Flowers: Model the Spreading Color

Color at the Backyard Worktable

At a backyard worktable, Imani is making paper flowers for a family gathering. She plans to dip the paper edges into blue water. Before she begins, she investigates how food coloring spreads through water. An adult helps her gather two matching clear plastic jars with lids, a measuring cup, water, and food coloring. The materials are for investigating and crafting, not tasting.

Imani labels the jars P and Q. She pours 200 milliliters of room-temperature water into each jar. She adds one drop of blue food coloring to P and adds no coloring to Q. She closes both lids. She keeps the jar type, starting amount of water, location, and observation times the same. Both jars sit together on a shaded, sheltered tray. She does not stir or shake them.

At first, P has a narrow blue streak near the drop, while much of its water looks clear. After ten minutes, the blue region is wider and reaches farther down. After twenty-four hours, P looks evenly pale blue from top to bottom. Q still looks clear. Imani can see the blue color, but she cannot pick out separate specks of food coloring in the water.

Next, Imani measures out half of P's blue water and saves it in a third closed jar. This leaves 100 milliliters in P. She adds 100 milliliters of clear water from Q to P, closes the lid, and gently turns P three times to mix. P again contains 200 milliliters of liquid. Its color now looks evenly blue but lighter than before. Imani records the amounts as well as the color change.

To explain her observations, Imani plans particle sketches. In these models, a dot stands for a particle far too small to see by eye. A sketch shows a small sample of particles, not the huge number in a whole jar. Dot colors identify materials, and the drawn sizes are not real particle sizes. Water particles also belong in a complete model, even when a simplified sketch leaves them out.