Teachers can re-assign a previously completed objective for students to replay. You can view steps on assigning an objective here - How do I assign, edit, or reorder class and individual assignments?
When an Individual Assignment is set, students will be prompted to play or replay it. Students will collect puzzles when replaying the assigned objectives.
When a Class Assignment is set, only students who have not yet completed that content will be prompted to play it.
Students who are replaying an objective will show Replay under the objective progress bar on the Student page > Objective tab > Assignments subtab.
The student will not retake the pre- or post-quiz.