If you would like to split the graded score report for your student(s) for a certain semester, quarter, or time period, you can do this in your Dashboard under the All Results tab. From there, scroll to the bottom of the page where you will see these two dropdown boxes:
Select the parameters you would like to have for the desired lesson/test numbers of the report and hit "Apply Filter." The scores at the bottom will be recalculated based on the filter parameters. The changes you make here are not permanent. You can come back at any time for another customized score report.