I can't recall the weight but it's just standard fishing line, nothing fancy at all. I bought it in 500 yard rolls for $4.00 each. We've had two lines be snapped by hawks flying into it! One left two feathers wrapped in the line as well!
You made the comment "I don't want to take a $5 chicken to the vet." Disgusting. If you don't have money to take care of your animals then you shouldn't have animals. They are life and shouldn't be treated as throw away commodities just because something is wrong with them.
Fishing line works. Period. We can argue all day but I have 1700 hards of line up over our coops and no chickens have been taken since. Hawks require clear path to swoop down. The line breaks up this path. Our line is attached to flag poles all around the yard (a sat view of our yard is...
Have you tried asking the school to provide them with a bigger area? It wouldn't be too expensive if you rounded up all the students who cared and worked together!