Divide your assignments into major categories, such as homework, class participation, quizzes and tests.
Assign a percentage weight to each category based on the importance of that category. For example, you may feel that tests are more important than homework. Therefore, you might use the following percentages: homework- 10%, class participation- 20%, quizzes- 30% and tests 40%.
Record your students' grades in each category.
Calculate a student's average within a certain category. Add the grades together and divide the total by the number of grades in the set. For example, a student may have scored the following test grades: 83, 87, 90 and 76. Add these values to get 336. Divide 336 by 4 to get 84.
Multiply a student's average in a category by that category's percentage weight in decimal form. In this example, tests are worth 40 percent of the whole grade. Divide 40 percent by 100 to get 0.40. Multiply this figure times the average, which was 84 to get 33.6.
Figure each student's grades for each category in the same manner and add all of the totals together for the final grade.