The IB progam typically takes place within a students junior and senior years of high school. Now I cannot remember the specifics of the courses but they are very comparable to AP classes. When IB took over at my school, they replaced all the AP courses.
There are 2 parts of the IB program.
1. Full IB Diploma student. The full IB Diploma student will be required to take a certain amount of courses and be further tested in said courses. All courses are divided up into 6 categories (now I cannot remember exactly what the categories were called but I'll let you know what was available at my school):
a. Language 1 or the native language of the studen. In my case that was English.
b. Language 2 or a second language. At my school in my situation, this was the equivelant to French 4.
c. Arts. Basically, we had the choice between visual arts or theatrical arts.
d. Experimental Sciences. Biology, Chemistry and Physics all fall into this category.
e. Social Sciences. History, Economics and Government all fall into this category.
f. Mathematics. Calculus and Math Studies were offered at my school but I think there's the possibility to take some form of computer science.
In each of these categories, there are higher level classes and standard level classes, a full diploma student is required to take 3 of each level. Any HL course taken will be taken during both the junior and senior years of high school. SL courses will be staggered between both years for example:
Here are the courses I chose and the year I took them in:
Junior year-
English HL1
Biology HL1
Visual Arts HL1
French SL
Senior Year-
English HL2
Biology HL2
Visual Arts HL2
Math Studies SL
20th Century History SL
In May my junior year I was tested in French since that course was over. In May my senior yeat I was tested in English, Biology, Visual Arts, Math Studies and History.
In addition to the courses, full diploma students are required to take a Theory of Knowlegde course that for us took place over the third trimester of my junior year and the first trimester of my senior year. It's sort of hard to explain the course but it's an extremely great class! Books that I was required to read included A Beautiful Mind, The Prince, Walden and Metamorphisis. It's not a religious course.
A couple of other things required for the full diploma are CAS hours similar to community service and the Extended Essay, a 4,000 word essay on almost anything.
2. The other part of IB!
Students can take any IB courses and not be a full diploma student. If it's decided that the full diploma is too much, rest assured that you won't be shut out of IB completely. Of the 500 students in my class, most of them took some sort of IB course but only 11 total ended up being full diploma students in the end. As PP said, it's HARD work.
Your kid is getting information as an 8th grader which is great. Prerequisite are to be taken during the freshman and sophomore years. For me (and I say this a lot because every school is different), in order to take IB Visual Arts or IB Theater, you had to have taken Art 1 & 2 or Theater 1 & 2, respectively. To take any IB Experimental courses, you had to have taken both accelerated Biology and accelerated Chemistry. To take any IB math class, you had to have taken math through at least pre-calculus. This wasn't all but it gives you an idea on why he's being approached now and not during his sophomore year.
I was an IB Diploma student and I wouldn't take it back in a heartbeat. I feel as if I was given so much more to take from my high school experience than I would have been given in the standard classes at my school.
Would I recommend it? Yes and no. I think it's something that isn't required to get into a great college but it'll prepare a student more than anything else would. In english, I read books that college grads were just getting to. But again, it's a lot of work. Intellectual capabilities aside, it can be draining to anyone. Other students will have the chance to take elective classes that won't be accessible to your DS since his schedule will not allow them.
He'll have a better grasp on what his opportunities are during this meeting. And I find it hard to believe there won't be anything out there for parents soon to come but if not, I'd advise looking over what they give him and speak with the IB coordinator at the high school with or without your DS.
I hope that helps, feel free to ask any questions and I'll do my best to answer them.