The first method for efficient studying I like to use is muting all electronics, this means phones, tablets, computers, and televisions. This is proven to help studying, because you will not be tempted to check every few minutes, and it helps you absorb the course material better without interruption.
Another efficient way for studying is to take notes. Detailed, or blunt, any type of notes you can write, even really quick terminology or vocabulary words, is fantastic. This helps trap the information in your mind.
If you have trouble remembering something, come up with a phrase. For example, if you have to remember, Glucose, Syrup, and Hydrogen, come up with a funny sentence you're sure to remember. "Gretchen sold Helium." This definitely has helped me in the past.
Perhaps have an adult or friend quiz you, or make flash cards to use and study off of, this is simple, and effective!
Another thing you could do is take frequent breaks, and play a video, (despite no electronics,) of the subject you are studying. Close your eyes, and listen quietly to the answers or information!!
I hope this was helpful..
