Look around your living environment and find an object composed primarily of a polymer(s). What polymer is it, and why does that polymer function well in that application? If the object is made from several polymers, focus on just one. Use the Internet as needed, and cite your sources. The plastic bag I get from DX dining hall to put my food in is made of LDPE. This polymer is proper for this type of object because it is not as packed as say HDPE, and the flexibility helps the bag become stretchy, making it easy to stuff a lot of overpriced food into the bag.