(edited below to add some links!)
What is included at upper elementary? What is the best scope and sequence to use?
Only the child can tell you that ;)
What is done in upper elementary will vary wildly - because it will depend on what was done in lower elementary. Some lower elementary children will have completed all the long division work; but almost all upper elementary scope and sequences have it there, not because you should wait until then, but because it should be reviewed and mastery assured.
The focus of upper elementary is to review everything from lower elementary and go deeper, go wider, do a LOT more personal and group research. This is the time to really pull things together. Lots of time and space for learning and exploring. Mathematics is one area that continues on, but still not with a specific lower/upper elementary break; geometry has all concepts reviewed either in practice or with album pages that go deeper; history reviews all concepts and adds just a couple of album pages specific to upper elementary; language is now about USING it, with the tail end of the analysis work.
If a child is starting elementary late, these experiences will be different - the children will work a bit longer - and that is ok! Just keep on going, following the child, don't hold them back!
:)
Some online samples, not to muddy the waters, but to show the wide variety of experiences that any particular upper elementary child can expect:
Not a scope and sequence but a
great blog by NAMC - linking just to the posts tagged as upper elementary.
I do not recommend any scope and sequence that is strongly segmented by grade level - recommended ages are fine, but anything that says "this must be 4th grade" or "this must be 5th grade" is ignoring a small but important set of Montessori principles. Look for Scope and Sequences that give ranges - freedom to follow the child.
(ETA: Keys of the Universe scope and sequences do give some specific grades, but are suggestions to help you with the sequence - not to be following rigidly)
Issues with Using the Table of Contents as your Guide:
Unfortunately, no, you can't just look at a
table of contents (most of the time) to get a general idea of scope and sequence because each album page might include anywhere from 1-15 (or more!) extensions, stages, activities, follow-ups, etc. that
might last anywhere from a week to 6 years. Many AMI album pages have a specific list at the end of the album page for "9-12 year old follow-ups on this album page" - thus the child is expected to show some level of review (in a variety of ways within the classroom or homeschool, or just have a review presentation if needed) then is invited to further/deeper/wider follow-up work options. Same foundation - now let's take another path! But typically not all of those fine details are listed in the table of contents.
Issue #2 with the table of contents: various "chapters" (which are there for adult organization, not for child sequence) might be covered back and forth over the course of weeks or months. The first 4 chapters of the mathematics album for example are covered at varying times in lower elementary - with little rhyme or reason for when to jump around except "follow the child". The fifth chapter of mathematics is begun when the child is ready - any age; subsequent chapters as well, while still overlapping with one another.
SUMMARY: Build a strong foundation in the primary and lower elementary years; so you have lots of time to explore and learn and discover throughout all of childhood without being bogged down by "must-have" and "should-have-dones" - just keep moving along and enjoy the journey!