Yes, you can reset students' assignments! This is especially helpful if students submits before they have finished answering questions or they do poorly on an assignment and you want to give them another try. Unlike "reassinging" an assignment, students will see their previous work.
To reset a student's assignment, go to the assignment's "Dashboard" and use the checkboxes next to students to select who you want to unsubmit. Then click "Unsubmit."
You can also unsubmit from the "Assignment Report." You can get there from the assignment dashboard or by clicking the button in the top-right corner of the grading page. Scroll down to where the student's name and score is, and you should see an UNSUBMIT button in the "Details & Actions" column. Click on that button and you will be prompted to reset the assignment.
Students will be able to see their previous answers to the assessment questions and redo them. They will be able to see your feedback and score on each short answer question. They will not see the correct answers on multiple choice questions, even if teachers have released scores.
While unsubmiting will reassign the final assessment questions, students will not be able to retake any previously answered guided reading questions. If you enabled Guided Reading Mode for students after some submitted, they will be able to see and answer those guiding questions when you unsubmit.