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:
Open System Preferences and go to Keyboard:
Select the Shortcuts tab. Make sure the box for "Use keyboard navigation to move focus between controls" is checked.
Additional settings for Safari Browser.
Open Safari Preferences:
Select the Advanced tab. Make sure the box for "Press Tab to highlight each item on a webpage" is checked.
"It is the mission of the Cleveland County School District along with parents, faculty and community to create a safe, structured learning environment for all students. This positive learning environment will enable all students to master the necessary skills to be college and career ready."