Letting go of the schedule (a little)

OK, this is hard for me.  B & K have gotten it into their heads to play explorer/survivor in the yard.  But it's SCHOOL TIME!   I know that this is one of the perks of homeschooling--that when my children are actively engaged in a healthy, worthwhile activity like imaginative play outdoors, I can let them do that and reign them back in for schoolwork later.   But I have a REALLY hard time letting go of my framework for the day as I see it.   I am learning, slowly but surely, the flexibility that is necessary and available when homeschooling.