How do you ask a girl to do it?

Far less than 1%. I'm fairly certain a condom works 98% of the time, and birth control works 99.8% of the time. That means you have approximately a 0.004% chance of impregnation. Of course, those percentages are off the top of my head. That, however, is with proper use but isn't factoring in the spermicide condoms they have these days. Really that's a 1 in 25,000 chance.

Also, most "sex-ed" classes are really just telling you abstinence is the best way to go.

You're correct..Well in my high school they didn't really preach "abstinence" only, the teacher just said if you choose to do it, these are the consequences that can occur. And granted about like 10-15% of the population of my high school was full of preggers anyways lol hell we even had a day care on campus(for faculty & students) that was also for the early childhood development classes.

birth control can be unsafe alot of times
its best not to abuse it

It depends on which birth control you use though (patch, pill, ring, IUD, Depo). Using both (condom for male & pill/patch etc. for woman) is actually a very good idea, it drops the rate of getting pregnant even lower vs. just using a condom(b/c they can always break & no, strapping up 2x isn't effective b/c BOTH can break as well) not to mention getting any STDs but I'm presuming that you would be with a person that is clean obviously.