Combine Plaster of Paris, water and tempera paint. The amount of tempera you add will determine how dark the coloured chalk will be. Pour the mixture into candy or popsicle molds and let dry.
Take the chalk out of molds and use for drawing on the sidewalk. This chalk will be most effective right after taking out of the molds.
Added Tips:
Used your chalk recipe. Kids very impressed.
Beside using dry tempera I added a small amount of acrylic craft paint for color and it worked great. We tried using paper coin tubes but found that difficult and messy. We did find that a toilet paper tube worked well or a 5 oz. dixie cup.
From: Felice Birdsall, a Teacher and Library Clerk at Bayview Avenue School, Freeport, NY.
Another tip is to line your molds or tubes with wax paper to allow the chalk to slip easily out of the molds