> No one is forcing a child in this setting to join in. <
Perhaps not. But kids at that age are impressionable, and generally want to please the teacher. I’m a Christian. If a Muslim public school teacher led an “optional” prayer in my child’s class, I’d go berserk.
What would my child be expected to do? Not listen? Get up and go to another room, and so maybe get a scowl from the teacher?
Much better that the public school teacher be removed from the equation entirely. Instead, instruct your own kids on how to silently pray and be thankful for their food.
I would instruct my kid to pray aloud and invite others to join in.