The gradebook is organized with students in rows and assigned activities in columns. You may need to refresh the page to show the most up-to-date entries for the gradebook, especially after assigning an activity.
Scores for each activity are determined on a pass/fail basis. If the student reaches the target score prior to the due date, the student will get the full possible points associated with the assignment. If not, the student will get a 0.
Note that clicking on the title of an assignment will take you to a page where you can get more information about your students' performance. For more information, please read How do I check my students' progress in Read & Practice?