We did it! Sidewalk chalk was a huge success...and so easy. We even made a second batch today :) Here are a few of our materials: plaster of paris, powder tempera paint, measuring cup & toilet paper tubes.
The kids chose a few types of molds...
We even used food coloring to help intensify the colors -- plus, we only had black and yellow powder tempera paint.
Little fingers mixing away.
After 24 hours, we had homemade chalk. It was trial and error: toilet paper rolls stick to the chalk, making it difficult to peel away. Ice cube trays, popsicle molds and a sandwich cutter did a great job for shapes.