For a video overview of this topic, please see this article

With MatchMySound you can set an assignement of just a section of a piece. If a Learner is having trouble with just one area of the exercise or needs to work on a specific few measures, you can select those measure and send it as a separate assignment. 

• Open the Song or Exercise you want to use.
• Click on Sections then the Mark New Section button in the toolbar.
• Drag the start and end points to include the measures you wish to assign. The length needs to be at least 5 seconds long.
• Click Assign
• Choose a Learner from the drop down
• Leave the Section selection as Current
• Change advanced options if needed. For more information about Assignment Advanced Options, see this article
• Click Assign.