I won a package of Crayola 3D chalk and gave it to the girls this morning. They were so excited to try it out this afternoon. When you put on the glasses the different colors do seem to float off the ground and a different heights. I have seen these in stores but was not sure how well they would work on cement. The examples on the box all show the drawings on blacktop and we have only a sidewalk. The glasses are a little small to fit over my glasses but I still can see the 3D effect. The glasses do fit fine over Princess A's glasses just fine. We have been outside for over 90 minutes and I am sure they would stay out a few hours more. I know we will be put here many times until the rains comes.