And a very advanced education system where calculus and physics are taught in 5th and 6th grade

BS. i took 5th, 6th grade in Soviet Union. we had no calculus and purely conceptual, primarily arithmetic oriented physics.

dunno about 5th and 6th grades, but yes, physics and calculus are definitely introduced in middle school (junior high for our american friends).

physics in 5th grade,an equivalent of American precalculus in 9th grade and calculus in 10th grade

Not according to this: http://www.emis.de/projects/Ref/doc_ems_pdf/EMS_NATIONAL_PRE...

"Traditionally, in grades 7–9 mathematics comprises 2 school subjects, geometry and algebra that are taught in parallel (e.g., 2 hours per week for geometry, and 3 hours for algebra). In the senior school [16-17 years old], also two subjects are taught, geometry and algebra and elements of calculus. In grades 5 and 6 (and in primary school) we have a united course of mathematics."

For comparison, the US high school math curriculum (for students 14-18 years old) is generally algebra, geometry, precalculus/trigonometry and calculus, although students can still graduate with just algebra and geometry.

That said, I don't doubt that there is a cultural and educational emphasis on math in Russia.

"Also, to eliminate any confusion, grades 5 and 6 in Russia are roughly the equivalent of grades 7 and 8 in the US."

Where did you get that from? When I studied in Russia we'd skip grade 4 (don't ask me why!) and most students started 1st grade at the age of 7. Meaning grade 5 really corresponded to grade 4 in other countries.

Upon review it looks like it might only be shifted 1 older or possibly the same, but it's unclear. Russian education apparently starts a year later than in the US and, until the 90s(?), ended/still ends(?) a year earlier and, as you noted, didn't/still doesn't(?) include a 4th grade. The presentation from 2000 on Russian math education I linked to also states that "number 4 is usually omitted" and that the system "has been in the state of permanent reorganization." Thus, it's not entirely clear to me how the grades match up, so sentence excised.

For the past 10 years it's just about having the money to pay for your exams. Education has gone downhill since the collapse of the SU. Russia doesn't need mathematicians or physicists anymore. My uncle is a professor and gets paid well under $1K a month. All that matters is what the price of oil is, and how much they can export while the old refineries still haven't fallen apart. Russia's income is purely from oil & gas now.

This was around '89? I think they were switching from a 10 to 11 year program and whoever was in school already at that time skipped a grade.