Biology class extra credit: the male reproductive system.
The girls first collect his sperm and show it under a microscope.
Next, they castrate him and dissect the testicles to show the working parts.
They force him to cum again and examine the produced fluid result, showing no sperm or a very reduced count.
Finally, they take his penis from him and dissect it too.
This occurs in front of a class of fascinated girls and boys with uncomfortable erections.