I made some yogurt yesterday with six cups of milk. I let it incubate, cool, and then I strained it for several hours to make it thicker. The whey that I strained off was about one and a half cups in volume at the most. The remaining yogurt didn't seem like much, so I measured it. It was only three cups.
How did one and a half cups of yogurt disappear? What am I missing here...?