Americans, did you learn about slavery in school?

Yeah. I first learned about slavery (and, for that matter, since it was a popular cause at the time, south Asian sweatshops and child labor) in first grade. This was a pretty run-of-the-mill public school, and obviously for first grade we were taught at a level relative to our world knowledge, very ideologically rather than politically oriented: people oughta be free, kids should be in school not factories, look at what you have and compare it to what they have/had, etc.

But my first grade teacher was a flat-earther so I didn't really have that going for me.

Of course, several times. This was in public school in redneck Jacksonville Florida, in the 60's and 70's.

Of course. You are taught about it quite early on. The earliest I can remember is around the 3rd or 4th grade. Usually brought into context with Abraham Lincoln as president.

I'd be surprised if any major school skipped slavery. They just drip so much propaganda over it that it confuses the core concepts.

Like my textbooks in late 90s suburban Atlanta that referred to the civil war as "the war of northern aggression", and that the war wasn't actually over slavery anyway but instead 'state's rights'. And teachers telling us that the south treated their slaves so well that chattel slavery was actually better for them than being free. "Why would someone destroy their own property!" was a verbatim argument I heard in class from an AP US History teacher during a lecture.