We have an "integrated" curriculum where they do some of each every year. So my son is in the first year of the 4 year high school sequence and he has done some algebra, some geometry, some statistics, some probability, some trig. They will go into more depth on each of these and add other topics for each year. In some ways it isn't a bad idea, except it really causes problems if you move in our out of the district because the kids are way out of sync with the rest of the world!