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:
Welcome to my online classroom.
1st & 7th Hour Computer Apps II – 8zcmda
3rd Hour Computer Apps I – pr72hq
4th Hour – Computer Apps I – mea5rx
Yearbook/Desktop – 937dy9
Keyboarding – mp96ba