Every college degree requires a certain number of credits or units for you earn so that you can graduate. Amidst the overall requirement, there are certain credits or units that are required. For example in a credit system, if you are pre-med, your college might require 120 credits for you to graduate. Of those 120 credits, 60 have to be in science courses. Of those 60, you are a required to take anatomy, biology and chemistry. Once you reach 120 credits and fulfill all of the requirements, then you are able to graduate.
One method of calculating credits or units is to give every class an equal value. This means that your physical education class has the same value as your biology class. This method of calculating credits and units is ideal for someone who is transferring to a new school on the same equal-weight system. This also means that each class is equal when calculating your grade point average.
Another method of calculation gives merit for the amount of time that is spent in the classroom each week. For example, if your algebra class meets twice a week for 90 minutes, then it is worth 3 units or credits because you are in the classroom for a total of the 3 hours. If your school uses a weighted grade point average, then the classes where you spend most of your time will be worth more than others where you spend less.
High school students can earn collegiate merit by taking advanced placement (AP) courses. These courses are taught at a collegiate level and require the student to perform collegiate-level work. At the end of the course, the student must take an AP exam. The scores range from 1 to 5. If a student scores a 4 or 5, he might be able to get merit from the college or university. To receive merit, the student must apply through the registrar's office. If accepted, this reduces the number of credits or units the student will need to take while at the college or university in order to graduate.
Some colleges and universities operate on a quarter system rather than the traditional semester. If you are transferring to a new school that is on the opposite system, then you need to either multiply or divide your units in order to translate them to the other system. For example, if you are at a quarter school that awards 2 units for one quarter of English and you are transferring to a semester school, then you need to multiply by 2 in order to get 4 units for the English class. Conversely, if you are going from a semester to a quarter school, you would divide those 4 units from the English class by 2 in order to get the quarter value of 2 units. Note that different schools might have different conversion ratios, such as multiplying or dividing by 1.5, depending on their policies and procedures.