You need to pull the entity into the workflow. Add a workflow attribute-
Then Add an action to set the student ID. The lava in the screenshot is:
{% assign allStudent = Workflow | Attribute:'StudentIds','RawValue' | Split:',' %}
{% for Student in allStudents %}{{ Students }}{% break %}{% endfor %}

Then in the notification email action add this lava:
Link to Student's Profile in Rock: <a href="{{ 'Global' | Attribute:'InternalApplicationRoot' }}Person/{{ Workflow | Attribute:'Student', 'Id' }}">Student</a><br/>
which will add a link to the students profile.
*Content for the lava was provided by Mark Lee.