A thick, stiff type of paper that's often used to make boxes and other things like signs. It's stronger and harder to tear than regular paper.
cardboard
a shiny, hard material found in rocks. It can be bent, shaped, and used to make many things we use every day, like coins, cars, and even the wires in your phone.
metal
a natual substance (from nature) or made by people. Everything around us is made of it
chemicals