A big 32-hour workweek test is underway. Supporters think it could help productivity

More than 3,300 workers in the U.K. are participating in the largest pilot of the four-day workweek. The experiment will last six months as researchers track how people respond to having an extra day off. (Justin Tallis/AFP via Getty Images)

For the next six months, thousands of people across the U.K. will be working 32 hours a week in the largest four-day workweek pilot the world has ever seen.

The experiment includes more than 3,300 people across 70 companies in industries ranging from health care to local fish and chip shops. It's being put on by 4 Day Week Global, the 4 Day Week Campaign, the U.K.-based think tank Autonomy, and researchers at Cambridge University, Oxford University and Boston College.