(a)Mary is in the classroom but Jane is in the hall. A door separates the two and the handkercheif is slid part-way under the door.
In reality, though, Jane has taunted Mary just one time too many with her "I'm smarter than you" gibes. As the red mist descends, Mary's fist flies through the "safety glass" in the upper part of the door causing shards of wire-embedded glass to raggedly lacerate Jane's left external jugular vein. "No biggy", I hear you say, "haemorrhage from this superficial vein can be dramatic but is easily controlled by direct pressure"; but the wire in the wire-reinforced glass has a high nickel content and Jane is allergic to cheap jewellery!