Tests are curved by adjusting scores to a predetermined distribution, such as a bell curve, to determine final grades. This helps account for variations in difficulty and ensures fairness in grading.
In some states, Standards of Learning (SOL) tests may impact your final grade, while in others they are used for evaluation purposes. It's important to check your school's policy to understand how SOL tests are factored into your overall grades.
You can study for tests and do extra credit.
Teachers determine grades for student work by evaluating the quality of the work based on criteria such as accuracy, completeness, organization, and understanding of the material. They may use a variety of assessment methods, such as tests, quizzes, projects, and class participation, to measure student performance. Grades are typically assigned based on a predetermined grading scale that reflects the level of achievement demonstrated by the student.
It is simply the sum of all grades divided by the number of grades: the arithmetical average of the grades. If some tests were more important than others then you might take a weighted average whereby you attach more importance (weight) to the important tests.
Get scores or grades on tests, homeworks, and quizzes.
Apply and have good grades. Take the tests.
Get scores or grades on tests, homeworks, and quizzes.
It is simply the sum of all grades divided by the number of grades: the arithmetical average of the grades. If some tests were more important than others then you might take a weighted average whereby you attach more importance (weight) to the important tests.
Study, understand and practice
If those grades are weighted equally, then no.
Yes,5th graders can get good grades. All you have to do is work hard and study. Plus, if you remember stuff for tests, hopefully you'll get a good grade. 
No, pregnancy tests for humans do not work on cats. Veterinarians can determine if a cat is pregnant through physical exams, ultrasounds, or blood tests.