Renewable Resources:
Nonrenewable Resources:
hydroelectric power coil and oil
apple trees gemstones
wind power steel
I'm not sure how exactly you wanted this question to be answered. You're either talking about the symmetry where animals would have two legs or two arms for example and thus producing a pair of each muscle on both sides of the body, or you're refering to the development of agonistic and antaonistic muscles where each of them served a different purpose; either extending or contracting.
You could have made sure the books were the same weight and your friends could have done it at the same time as you
