Wal.... that depends if it was snotrags or real handkerchiefs. Snotrags come in all sizes because, of course, they start out as RAGS, for which there is no standard size. Gent's hankies OTOH would be fine linen....

How big is a magician's handkerchief-- the ones we see nowadays (on TV hiding rabbits) are purdy big. The "standard" bandana, now, is about 12"--- but this is beside the point.

Because-- when you make them into ropes, you fold them on the diagonal, which is the direction the fabric wants to stretch the most and also probably the strongest: force pulling on it will pull not across warp or weft (like where one might want to tear a rag and it will tear quite easily)-- but on the "bias," where the threads intersect.

So to really get to the heart of this you would need to know not only how biased your escapees were, but also what fabric was used and how tightly it was woven. Batiste, for example, is a loose, almost sheer weave, so it would stretch a lot.... plus take very little of the corner-fabric to make a very strong knot. Anyone who has ever tied a bandana into a bikini can tell you THAT.

(As well as that wet fabric behaves differently from dry.)

But then you also need to know what fibers might have been used because cotton batiste would not be very strong but linen woven that way....

My head hurts.

But you can see for yourself, now, how to handle this "feasibility" question with kids-- invite them to bring different fabrics and sizes and play "escape" (but not from the classroom if it's not on the ground floor, LOL).

~Susan