I don't believe in crippling sparrow or starlings. I also disagree that handling the pest problem is sensitive at schools. Haul your lazy a** to the site between 4 AM and 8 AM and you will find very few observers for any technique you use.
Might I use this emoticon without causing offense?
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Left school last night at 9:00pm after working with martins 'till dark, got here at 6:30am to observe same martins at dawn

Not much going on that I can do with martins at 4am. Although I did do that 24 hour water sampling project with a kid earlier this year that had us out round the clock (sampling every three hours). So its always something.
OTOH, I get like three months total vacation each year so I suppose it all balances out.
Sparrows are not "crippled", merely deprived of their tail feathers, a not-uncommon occurrence with wild birds. Starlings, on the rare occasion that we have to I just killed 'em. Especially using that one handed skull-crushing technique I can kill them even inside the trap gourd, pretty much in just a couple of seconds. Both the starling and the sparrow I killed this week were dispatched during the school day during passing periods, no one the wiser.
As for the lethal control issues in a public setting, perhaps your schools are different.
OF COURSE I could kill and lie about it, but I believe telling the truth has value, especially in a educational setting. When I DID kill and talk about it, that is all the kids talked about, rather than all the many issues and facets martin-keeping can teach about.
Your mileage may vary.....
Mike Scully