Cut paper to fit the inside of a salad spinner. Squeeze 3โ4 small dollops of washable paint onto the paper. Close the lid. Hand to child.
Spin the handle. Open the lid. Wow.
Squeals. Demand for more colors. Immediate request to do it again with different paint placement. Kids will refine their "method" โ more dots, less dots, this color in the middle, etc.
Try only two colors and watch them blend. Use food coloring on white paper for a less-messy version. Spin slow vs fast.