This problem occurs when the student's Chromebook is zoomed in or out and the student cannot see the entire screen. The student may not able to see the submit button to submit their answer.
If the login screen is zoomed in the student may receive the "Workstation Readiness Check" error message when attempting to start the test. The resolution will need to be changed from the login screen prior to starting the test. More information for this can be found here: Chromebook Resolution Issue
To make the page bigger, Press ctrl and the plus key ( + )
To make the page smaller, Press ctrl and the minus key ( - )
To reset the zoom back to normal, Press ctrl and the zero key ( 0 )