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:
Daily Schedule
1st Block 8:20 to 9:40
2nd Block 9:45 to 11:05
3rd Block 11:50 to 1:10
4th Block 1:15 to 2:35 (Planning/Conference Period)
5th Block 2:40 to 4:00