It was a fantastic experience. I don't think there was a name for it when we started--I've been using the name retroactively since I've learned about it because it describes what I grew up with better than anything I could come up with.
When my mother decided that we needed to know US geography, my mother, my sister, my brother and I got in our beat-up minivan and drove the US for two months, camping and eating PB&J out of a cooler. I may not know the capitol of New Mexico, but I know the climate, and the geography, and what the cities are like, and what the people look like. If I need statistics or facts, I can look them up. Looking things up was a bit part of unschooling--we spent hours every week in the library, learning how to use the reference section, learning how to find information, and how to compare resources.
Math was the hardest part to learn--my parents were not math people, and they ran out of things to teach me at about algebra. But I was interested, and so they found a local engineer who agreed to tutor me before work in exchange for cutting his grass every week. He taught me out of the same textbook I used later in college, and he chose harder practice problems than my professor did.
By state law we were required to take standardized testing every other year, and we actually did it every year--all of my siblings scored above the 60th percentile in everything, and above the 90th percentile in most things.
It had down-sides, of course. When I went away to college, I didn't know how to take notes or format papers, and sitting through a two hour lecture was painfully boring and unproductive--I'd learn more by reading the textbook in class than I would listening. The upside was that I knew how to learn things, and how to motivate myself to get things accomplished. My grades were not great--that's a problem with unschoolers, because you haven't been taught to be motivated by letter grades. You learn things to learn them, and if you feel like you've learned something, jumping through hoops to please a professor doesn't seem like a useful way to spend your time. I got an A in any class I cared about, and a B- in any class I didn't--that was my threshold for 'passing'.
Unstopping can be very productive, and is a valid way to learn things, if it's 'taught' by someone who is curious themselves and is willing to try things. You have to grow up, I think, in a household that values education and learning for it to work, but I don't feel at all like it has held me back.
