The very name "American Curriculum" is a misnomer, since technically there is no such thing in the way that there is a National Curriculum of England, or a French national curriculum
All fifty states and most major cities/school districts (often county-wide, not just one city) set their own curriculum frameworks, priorities, funding, standards, tests and scheduling. The US Department of Education guides, recommends, and sets national standards, but has no statutory control or power over state or local authority. Therefore, quality and standards vary between states and districts, with some being outstanding, some ghastly, and most working most of the time to build a better mousetrap. At any given time, there are interesting educational experiments going on throughout the country, and sometimes some of them get it right.
However, even in this giant national educational laboratory, there are a good many things about which one can generalize (as in the above description about neighborhoods and school districts). Generally speaking, schools calling themselves American, or that say they use an American curriculum, offer a wide range of courses from kindergarten to twelth grade, with the guiding principal that children will eventually know their own minds better, and make better choices about their own fields of study, if they have a good sampling and basis in a number of areas extending through their high school years.
Elementary, Middle School, High School
The lower grades of elementary school (Kindergarten through 5th grade, roughly ages 5-10) allow for a good bit of play and social interaction as children begin to learn letters, numbers and reading (“knows letters up to L; plays well with others and handles scissors well; still overly enthralled with paste” sort of thing). Science, social studies, languages, the arts, and physical education are brought in at various grades and are taught with varying amounts of skill and enthusiasm, depending on the state’s, district’s and/or school’s legal mandates, emphasis or funding.
In middle school (6th grade through 8th, roughly ages 11-13), course work is broad-based, but often with possible streams splitting off into more rigorous college-bound directions to prepare students for more advanced high school work and pre-requisites (ie pre-Algebra), or less academic work demanding competency in basic skills in preparation for vocational school (supposedly - of course, there are way too many schools that do an incompetent job at either of the above, but that’s what this Guide is for). Decisions as to which stream a student follows are made by some combo of administrators, councilors, teachers, parents and student.
The high school (9th grade through 12th, roughly ages 14-18) curriculum can be made up of still more streams, such as Honours or Advanced Placement, IB Diploma programme, a magnet programme in the arts, math, aeronautics etc. But all tend to have a broad-based curriculum that requires students take a total of 26 credits in order to graduate with the basic High School Diploma. The twenty six credits are mostly year-long or semester-long required and elective courses, and include a certain number of years of English, social studies (including history - world, US and state/local), science, maths, arts, PE, possibly languages etc. The IB has its own requirements that often mesh well with this curriculum, although IB and AP courses are more rigorous and much more extensive than the standard course work (at best, they give students many more interesting options for study).
Report Cards, Grades and Transcripts
Most schools have report periods every quarter or 6 weeks. Generally speaking, secondary schools evaluate students with letter grades (A-F or E) that correspond to numbers (A=4, B=3, C=2, D=1, F=0). These individual course grades are compiled to make a final average for the year, called a Grade Point Average (GPA). Many schools add "weight" to certain grades, depending on the degree of difficulty, so that an A in Auto Mechanics is only given 4 points, but an A in AP Algebra II might be 4.5 or 5 points. This means a straight A student who has taken 8 or 10 AP courses could end up with a much higher GPA than just a 4.0.
The compilation of all of his/her grades makes up a student's "transcript". The GPA is calculated annually, and finally it's calculated for the student's four-year high school career. The annual calculation establishes the student's rank in class. (This can get into a war of numbers, as top students feverishly recalculate their own and each other's ranks to try to figure out who will be #1- Class Valedictorian, always the one to make the speech at graduation.) Because requirements for graduation include a broad range of courses, it is always galling when an otherwise brilliant academic student is betrayed by his poor showing in Physical Education, or a promising English student just can't do math - unweighted or not, those classes have grades too, and can wreck a perfect 4.0.
There are no national curriculum exams in the US. Teachers for each course organise their own exams, class by class, and hold final exams for each term ("finals") and mid-term exams ("mid-terms") half-way through a term. Those have different weights towards the term grade than ordinary tests or quizes.
Classes might be scheduled every day for 50 minutes, every other day for 90 minutes, or in any number of variations that the school or district has set. Although some school systems go year round (with slightly longer breaks between semesters or quarters), most still break from June (or late May) til sometime in August (or early September)....a model originally designed so children would be free to help their families with the harvest.
Funding and Accreditation
Amongst the usual public and private schools, there might also be foundation schools or charter schools or magnet schools, some of which are public (paid for by the tax payer) but run like private schools. Contrary to popular belief, here and there in the US there are public schools which may provide as good an education as the very best private school money can buy.
NB One thing to look out for is whether that school is a "Blue Ribbon" school...about 300 state and independent schools are selected every couple of years for this award, which not only means the school had to complete an exhaustive self examination and miles long essay/questionnaire, they had to pass a peer-review and visit; it is above all an indication that the school is firing on all cylinders in order to be wonderful on multiple levels...always a good sign.
Private schools have even more leeway as to their form, rules, funding etc, but still have to meet state standards and those of accrediting boards; they also tend to offer a broad range of courses.
Above all, all American schools, public or private, must be accredited by one of the accrediting agencies recognized by the US Department of Education (see Accreditations/Inspection Agencies on the this site), or students may find it difficult to go onto an accredited college or university, and are likely to find their High School Diploma not worth the paper on which it’s printed. (There are exceptions to this rule, particularly if the college or university is interested in the (extremely high) athletic ability of said student. In that case, the universities can be so veracious they will barely require the student to be literate.)
Applying For College (University)
Class rank, grades, degree of course difficulty (Advanced Physics vs Beginning Car Mechanics), SAT scores, extracurricular activities, and community involvement (usually a certain number of hours) are all considered by colleges (universities) at the end of it all - an application process for which it is wise to plan in 9th grade and prepare in 11th grade, but which actually takes place in earnest in the autumn of a student's senior year. Applications are usually due in December or January, and acceptances mailed by the end of March.
NB: A student who cannot or does not complete the requirements for a HS Diploma can test for the General Education Certificate (GED), indicating that that student can at least answer basic questions up to a certain level of competence, but this is not a certificate that is of huge interest to most competitive post-secondary academic institutions.