An academic skill, I have greatly advanced in over my years in high school would be reading.
I have been required to read many books in my academic career, my absolute favorite piece of literature I have read would be "Of Mice & Men. Although it was not that challenging of a book we learned how to break down our readings. You begin to be more advanced in your reading looking for things like foreshadowing, symbolism, and allusions. Of Mice & Men, as an example foreshadowed the death of Lenny and he's troubles in many parts of the book. They used The bunnies, and the river to symbolize the innocence and arrogance of the main character of Lenny. Being forced to look deeper into my readings has made advancement in my understanding and my reading skills.