Of course, science isn't all chemistry and biology. Getting the kiddos all bundled up and ready for a snow lesson doesn't have to include beakers and Bunsen burners. In fact, it might just be a built-in lesson that piggybacks on an activity the kids began without prodding.
During a good frolic in the snow, the kids will no doubt get the bright idea to build a terrific fort from which they can gleefully launch snowballs. While you might not be crazy about the icy projectiles to the face, don't shut down the fun just yet: Building an igloo can be a really terrific lesson in both engineering and heat conservation.
Sure, the kids might not build an igloo in a strictly traditional Inuit style. But you can teach them some simple engineering strictures. For instance, instead of having each block flush on top of each other, incorporate small gaps between the top and bottom brick, so only the corners touch. That acts as a little arch that allows for a line of compression between the bricks, holding them in place [source: Wise]. You can also show them how to keep the floor of the igloo a little higher than the crack at a door opening, to keep warm air inside.