The same curriculum is given at 9-12 as is given at 6-9.
In terms of geography, for example, all of the general areas of the work need to be introduced in the 6-9 group in some manner; however, every presentation will not be covered, and many of the details are not reached until 9-12, when the children are interested in those details.
6-9 is an introduction to and a preparation for the work at 9-12.
What does this mean for us adults?
It means that it is not for US to decide what is upper elementary or lower elementary - it is up to the internal workings of the child to reveal to us what is appropriate for them at that time or not.
It means that when we have outside-of-the-child requirements (ourselves, local educational standards), we seek to find a way to provide what is necessary in the present situation, but not as a burden - focus instead on the child learning about fulfilling responsibilities, in an environment that respects their developmental needs.