Precum contains next to no sperm, so it's really unlikely to get pregnant from it. Apparently Sex ED universally exaggerates that chance so that people don't get the dumb idea to rely on pulling out.
I mean it's probably the right way to teach it that way, but you know, if someone theoretically had a bit of an impregnation kink, it sure would make them sad :(
Depends on how empty and clean the tubes are before they get busy.
If the paramour is a popular lad and has multiple callers (or just a frequent self-pleasure constitutional), the operating environment may not be a sterile field free from DNA.
It's interesting from a biology perspective, but still good advice to give those teenagers who spend their weekends going at it until they can't pronounce their own names.
I mean it's probably the right way to teach it that way, but you know, if someone theoretically had a bit of an impregnation kink, it sure would make them sad : (