1) Reboot the Chromebook (or simply signing out should work)
2) Click on apps (on the left side of the task bar at the bottom of the screen.
3) Select MAP Chromebook Testing App.
4) The student log-in page for MAP should appear.
5) When students are done, they will need to do a hard shut down (by holding down the power button) to get out of MAP (or at least that is what I have found).