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:
Schedule
8:00-8:45 Tiger Time
8:45-9:25 Computer Lab
9:25-10:30 Reading/Spelling
10:30-11:45 Math
11:45-12:15 Lunch
12:15-12:40 Recess
12:40-1:40 Language/Writing
1:40-2:25 PE/Music
2:25-3:20 Science/Social Studies