Ender's Game by Orson Scott Card was an excellent book. It starts from Ender's point of view then shifts quickly to 3rd person. His entire reason for being born was to save the planet from the buggers, insect looking aliens. On a usual morning he is eating breakfast with his family (Mom, Dad, Peter, Valentine) when Colonel Graff shows up and tells him he has made it. At age six he is taken to battle school in outer space and trained to fight. At the age of six years and nine months he is promoted to an "army", the normal age of promotion is nine years. He proves to be the best soldier in anyone's "army" and is soon promoted to commander of a jinxed "army" at age nine. The youngest commander ever before this was eleven. His army is full of newbies and losers and he teaches them until he is exhausted and then teaches them more. He never loses a battle; he makes them great. In one year he is promoted directly to command school skipping the required three years at pre-command.
Ender's Game uses exobiology, physics, medicine, physiology, and chemistry. My personal favorite is all of them but since I have to choose I'll go with exobiology. They use it when they cut open the buggers dead bodies and discover what is on the inside. The asteroid in which the command school is located was once a sentry point from the buggers" first invasion so they learn about them there. It is again used when Ender himself encounters an unhatched bugger queen and meets them on a more personal basis.
This is a New Wave as well as an Alien Beings book. It shows people expanding their knowledge and their living space by colonizing new worlds. The alien beings part is obvious, the buggers are alien beings and even though they are friendly, they can't easily communicate with us so they are considered the enemy.
I think the most creative idea was how the buggers lived and worked. The queen has conscious thought and the workers are like various arms and legs of a body.