What can I learn in 10 minutes that will help me the most in high school?

I will recommend you learn one or both of the two things I wish I had learned for success in high school, and each takes about 10 minutes to learn. The first is that in mathematics the order of operations is essential. It takes about ten minutes to read, memorize and make sticky-notes for mirror, door and refrigerator to remind yourself of the vital importance of keeping mathematical order of operations clearly and firmly in mind. The order of operations applies to algebra and is remembered as PEMDAS, an acronym for Please Excuse My Dear Aunt Sally. Eduplace.com says this about what the order is:

1. Do operations in parentheses.
2. Multiply and divide from left to right.
3. Add and subtract from left to right.

Elizabeth Stapel, writing for purplemath.com, says this (with dubious line-end punctuation) about the order of operations:

The "operations" are addition, subtraction, multiplication, division, exponentiation, and grouping; the "order" of these operations states which operations take precedence (are taken care of) before which other operations. ... "Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction".

The second thing concerns writing and is that the rules for commas are not there just to vex, confuse and torment me. They are there to allow me to sort out and communicate my complex thoughts effectively with you. A comma in the right place allows me to realize relationships between ideas, events, concepts or thoughts and feelings and to communicate these ideas (etc) and relationships to you. And why would either of us care that we communicate the relationships between ideas and things to each other? We care because that's what humans always want to do, communicate their complex realizations or imaginings about ideas and things to each other. And, conveniently, your teachers will be asking you to communicate a lot of these complex thoughts, realizations, revelations and imaginings to them.

The British have the best way of discussing commas. Americans rely on (what is supposed to make the use of commas easier but really opens Pandora's Box of comma mayhem) the archaic idea that you can "use commas wherever you'd pause or breathe in speaking." This advice leads to tortuous paths of misery. The British teach there are four types of commas: the listing comma, the joining comma, the gapping comma and the bracketing commas (plural because they always come in pairs, opening and closing bracketing commas).

Another strategy for teaching the same comma ideas is to call them the listing comma, the setting off commas, and the sentence structure commas. This strategy requires a bit more of a sophisticated vocabulary and grammar knowledge but can--when the time is right--open exciting new avenues of thought expression adventure.

It takes about 10 minutes to read and understand the explanation of the four commas--listing, joining, gapping and bracketing--memorize them and make those memory assisting sticky-notes to paste on mirror, door and refrigerator. The "four types of commas" is courtesy of the University of Sussex, Sussex, UK, and the more sophisticated approach is courtesy of Jordan Penn, J.D., educated at the University of California, Hastings College of Law.