It's really a no brainer for most kids. Even when presented with the opportunity to do something pretty cool during recess, very few things could be worth staying in for.
Last week I asked during morning meeting who might be interested in helping to stain some paper using tea to make it look sufficiently 1790-ish for a history project. Faced with the options of a) raise hand right now to sign up for something cool that I just heard about and want right now vs. b) think ahead to what I will want in four hours, lots of kids chose based on "right now." Many hands went up, including those of eager helpers who would ultimately become far less eager when 12:30 actually rolled around.
Recess? Or special project? Or....both?
As we were transitioning from morning meeting back to tables, Raymond came up to me to clarify a bit more about the timing of this project. "Is it during recess?" he asked. "Yes." I explained. "If you wanted to do the tea you would do that instead of recess." Raymond took in this information and went back to his table.
During snack, Raymond came up to me again. "If it were after recess, I'd do it."
Math came and went and still Raymond was wrestling with the choice between the two very enticing things happening simultaneously. He was also still desperately trying to find a way to enable himself to do both. Raymond clearly thought that if he asked enough times or in enough different ways he might influence my extremely poor scheduling decision.
"Do the tea-stainers get their recess later?"
Sadly, the answer was no, and Raymond really would have to choose between the two.
He opted for recess.