I was taught by Catholic nuns. In our sex education course, they told us condoms would not protect from aids because aids molecules were small enough to pass through the pores of a condom.
They had props. A small basketball hoop, with a big basketball that represented semen. Sure, the semen can’t pass through the hoop, it’s too big. Then they brought out a much smaller ball. But you see, aids is very small and can pass through easily.
When they were showing the semen part, they made sure to say that’s only if the condom was manufactured perfectly and not tampered with, which they said was only true about 20 percent of the time.