Sex ED in CPS public schools

Having gone to one of the private schools in Chicago, they spared no expense teaching us sex ed and health; leaving us admittedly more informed then one would want. I was approached by someone I know to buy a pregnancy test, I agreed and asked her the normal questions, When was the last time you had sex? Her answer? "September." Kinda shocked I went on to ask her the obvious question, When was the last "time of the month"? Her response: "A month ago, but I'm irregular." I answered, "well then why do you think you are pregnant?" Her answer, "I threw up 2 weeks ago."

I am honestly curious to how people just either disregard that type of education or don't have a school that tries to make the knowledge sink in. I have heard from some friends that health was kind of a joke as they make references to Mean Girls. I don't know what to think anymore.