Mrs Shelley says students at her college have been supportive of the action and most of those whose teachers are absent will be able to work from home.

BBC: Public-sector action: To strike or not?

But the fear of layoffs and the ever-faster pace of work mean many Americans are reluctant to be absent from the office -- anxious that they might look like they're not committed to their job.

CNN: Why is America the 'no-vacation nation'?