For Mac OS users, there is a system setting that may not allow you to tab onto several types of elements in a web page. To change this setting:
Class Schedule
Advisory period- 7:55-8:31
1st period- 8:35-9:28
2nd period- 9:32-10:25
3rd period- 10:29-11:22 Conference
4th period- 11:26-12:19
B-Lunch 12:19-12:49
5th period- 12:53-1:46
6th period- 1:50-2:43
7th period- 2:47-3:40