To be in complete control of something; to be fully informed or up-to-date about something. A: "How is the new project going?" B: "Right on track! Jen was on top of it while you were on vacation." I don't know how you're always on top of all the different student issues that are brought to your attention.

To get complete control of something; to become fully informed or up-to-date about something. A: "How is the new project going?" B: "Right on track! Jen got on top of it while you were on vacation." I don't know how you get on top of all the different student issues that are brought to your attention.