In LaunchPad, you can drop the lowest scores of all assignments reporting to any given gradebook category.
It is strongly advised that you have equal point values for all assignments in a category if you will be using this option. Why? The system will drop the lowest score according to percentage. If you have assignments with unequal point values, the result may not maximize the grades for the students in the manner you intend. Imagine, for example, a student has two assignments within a category with grades of 0/5 and 5/100, and you have selected to drop one score. The 0/5 score will be the one dropped even though dropping the 5/100 would be more advantageous for the student's grade.
Finally, click the zero that appears under the “Drop Lowest” column next to the category for which you would like to change the settings. Type in the number of lowest assignments you want to drop, and click “OK.”