My question involves labor and employment law for the state of: Illinois

if I am scheduled to work a shift from 4:45 to 10:15, with no scheduled time off the clock, can my employer require me to clock out for an extended period of time, but retain me on-call for the remainder of my shift?

The specific scenario in question was as follows. I was working at a pool, scheduled shift was from 4:45 to 10:15. @ about 6:30 they decided to close the pool for the remainder of the day, but they had a private pool party scheduled to come in after the public swim ended, this was scheduled from 8:15 to 10:15. When they told us we had to all punch out, they said we all we're required to return by 8:00 for the 8:15 pool party, and in the event that the weather was still bad and the pool party was canceled, we would not have been allowed to punch back in. Is this legal?