How to assign an unscheduled assessments

To assign an unscheduled assessments, click the Manage button of your desired course and then click the Instructor Tools button of your desired section.
Click the Assessments tab and then click the settings menu next to the unscheduled assessment created by you, and select the Assign To option.
A modal box will open, select the students to whom the assessment is to be assigned, provide the test start on and due date, and time allowed for the test in minutes. Finally, click the Assign button.