One of the staples of kitchen chemistry for kids is making sugar crystals or rock candy. Why not? It is educational and it tastes good, too. [Science with Screens] has a different kind of crystal in ...

Q: My wife and I have an outdoor patio built with colored, precast-concrete paving blocks. It doesn't take long each year for black mold and mildew to start growing on it. We also have an issue with ...