Perhaps do something with the mountain of snow, a la Andy Goldsworthy.
Expolre building maps as part of the civic process. The Aurora Project I
think it is called, at least used to offer tools to map areas of any
town for which there was a US survey satellite map. The kids can use
their key and map out, say, their city park, the paths and trails, the
trash cans and benches, and then make suggestions to the city about
where they might need more, etc. The demonstration I saw at GIS day at
the state capitol was excellent.