Final answer:
Time zones become earlier as an individual travels east across lines of longitude due to the rotation of the earth on its axis.
Step-by-step explanation:
The most accurate statement the teacher could make about time zones is that each time zone becomes earlier than the previous one as an individual travels east across lines of longitude. This is because the earth rotates on its axis from west to east, causing the sun to rise earlier as you move eastward. As a result, the time in each time zone to the east is ahead of the time in the previous time zone.