As the winter solstice nears and the sun sets earlier and earlier each night, December's evenings afford even the youngest members of the family the opportunity to do some stargazing. Choose a quiet room with a large window and a clear view of night sky, and turn off the lights so you can best see the sky. A telescope will help you see a bit better, but isn't necessary -- many constellations are visible to the naked eye.
If you enjoyed stargazing over the summer, show your children how the winter's sky is oriented differently from that of the summer -- constellations and planets have shifted positions. Different star groupings and planets are visible now, while others you might have seen in the summer have now passed out of range of sight. In the northern Hemisphere, you're likely to see Orion, for instance, while those easily recognizable Big and Little Dippers of summer have rotated out of view. If you live far enough north (and have kids who can stay up late enough), you might get to see the Aurora Borealis.
And even though one doesn't need quiet to watch the stars, a grandmother we know once told us that one can see better when one makes less noise. Encourage the kids to give her words of wisdom a try for five minutes, and see how much of the universe becomes clearer in the silence -- for yourself as well as them.