Good insulating materials for science project?

Question

I have to make a cardboard box house that can stay cool. Can anyone name me materials that would keep it insulated? Anything easily found in the house that is.

Answer 1

Newspaper works surprisingly well.

Answer 2

Plastic foam is one of the best insulators that can be found around the house.  

Polystyrene foam (the kind that crumbles if you break it; coffee-cup foam) is better than polyethylene packaging foam (the kind that has a soft, waxy feel).  You can cut and hot-glue the polyethylene type of foam easier though.

When I need foam like this I look in the dumpster first; the plastics foam shop second.  Walmart has polystyrene foam in the hobby/craft dept.