Your grade point average, or GPA, measures your academic performance by assigning a numerical value to each grade--"A" carries a value of 4, "B" corresponds to 3, "C" to 2, "D" to 1 and "F" to 0. GPA for a given semester or year comes from dividing the total number of credits you attempt by the number of points. For example, if you have three A's and one B over four courses worth three credits each, you have 15 points and 12 hours, for an unweighted GPA of 3.75. If your school uses a weighted GPA for advanced placement courses, you may have a higher or lower value based on the number of credits each class gives.
The current form of the SAT Reasoning Test, introduced in 2005, tests students on three categories: math, critical reading and writing. According to the SAT College Board, the SAT consists of three sections: two lasting 25 minutes each and one lasting 20 minutes.
Another standardized test used to test college readiness, the ACT, focuses more on science and math than the SAT. Some technical colleges or trade schools may prefer you to take the ACT to enter, rather than the SAT.
Colleges require a high school diploma or the equivalent of one--in most cases, the GED, or General Education Diploma. According to the GED Testing Service, the age requirements and fees for taking the GED differ from state to state.