I read about making borax crystal ornaments and thought they seemed so simple, interesting, and pretty that we should make some ourselves.  It was a Christmas craft and science experiment in one.  We bent pipe cleaners into shapes (Cedar’s, on the upper left in the bottom picture, is a bee), mixed 3 tablespoons borax per cup of hot water in mason jars, and suspended the pipe cleaner shapes in the jars.  They soaked overnight and in the morning we had crystal ornaments.  The kids are very excited about them.