When you make assessments available to students in their Mastery Connect Student Login, they can take assessments without a test ID. The Mastery Connect Student Login is a premium feature that is only available if your school or district has integrated their Student Information System with Mastery Connect.
Open Assessment Editor

Click on Trackers, and select the tracker that contains the assessment you want to assign.
Hover over the title of the standard that contains the assessment, and click on Assess.
Open Assess Tab

For a single standard assessment, click on the Assess Tab [1]. For a Multi-standard assessment, click on the assessment title [2], and then click on the Assess Tab.