While their sister was snowboarding, I took the three youngest to a great free sledding hill in Frisco. If you get a chance, the adventure park has free sledding and rents sleds if you need one. They even have a public restroom.
Between the snowboards and gear, we didn’t have much room for sleds, so we brought our inexpensive disks. They didn’t hold up well, but we still managed to have great fun.