Regardless of race, there are many young women who intentionally become pregnant out of wedlock. They don't care about birth control because they don't want to prevent pregnancy. Ramping up sex ed and contraception at school isn't going to make one iota of difference to them. They want those babies, period. They aren't shocked or dismayed when they get a positive pregnancy test--they are happy!
And the young men are happy to oblige them. The guys know how to use condoms but they don't want to, and the young women certainly don't encourage them to because they want to be impregnated.
A woman who has three children by three daddies before she's 19 years old certainly knows about the birds and bees. She knows how to prevent pregnancy but she doesn't want to.
That's the real problem. Sex ed isn't going to help those young women with their real issues.
This seems to me to be a whole lot of speculation and generalization. Do you have any evidence that supports this?