It was late march when the vans first started showing up at your school. The school never said anything about it to anyone, but slowly people were beginning to disappear from your classrooms, not a lot mind you but a few. Then one day you go to school and find that the entire thing has been enclosed in a giant plastic sheeting system. Along with that the black vans are parked all the way around the building and the only way in was right through the front door. During your home room class there is an announcement over the loudspeaker for all the students to meet in the auditorium.
When you arrive you see several men (including your principle and all the staff) wearing large plastic chemical suits) The principle starts off with a short speech about school pride and then gets to business... He explains that all of your parents have signed permission slips for you all to join in a large experiment. The exact details of which include everyone becoming turned into the opposite gender (amongst other changes) and this would continue till the end of the semester. At this time there was a half awkward laugh spreading through the audience as though it were a joke, but then as everyone realized the seriousness they began to yell and jeer at the principle, and some even tried to run for it.
Those who ran only found chained doors barring their escape and no way to get out. Soon large billowing clouds of lightly colored gas filled the whole room. People tried holding their breath but it failed them soon they were inhaling the noxious fumes and in moments the whole place was filled with unconscious bodies. A medical team goes around checking everyones vitals... Everyone was fine, in a manner of speaking. On a molecular level everyone was changing. Male to female , and female to male. Along with the twist of an additional change. All the new females grew features of one of three animals cats vixens or rabbits... meanwhile the new males grew features of Horses Dogs or Foxes. In matter of hours you come to in the gymnasium still weary from the gas and look at your body to see whats become of you....