01Inferred
Russia is not mainly earlier. It goes deeper and broader by 15–17.
At age 11 both systems have about the same number of school concepts at fluency. After 12 they separate. For a concept both teach, timing usually differs by a year or less.
See the two clocks →
02Secondary
Primary school builds something different in kind.
Multi-step word problems with schematic models, letter equations from grade 1–2, and "=" read as a relation. Motion and work problems are fluent in Russia by 10–11; in the US they appear as Algebra 1 exercises.
Compare the problems →
03Secondary
44 concepts reach fluency in Russia's standard track but not in the US standard track.
24 of them by grade 9: number theory, Vieta, rational expressions, three years of axiomatic geometry, vectors. The reverse holds too: 17 US-fluent concepts, mostly statistics and modelling, that Russia leaves thin.
Where the gaps are →
04Secondary
The mechanism is structure, continuity and teachers, not genius.
Daily mixed oral review, one coherent textbook line per stage, 5–6 math lessons a week in grades 5–9, and proof for everyone from 13. The best-evidenced pieces also work in US classrooms.
How it is taught →
05Secondary
Strong on curriculum tests, average on applied ones.
TIMSS 2019: Russia 567 / 543 vs US 535 / 515 at grades 4 / 8. PISA 2018: Russia 488, near the OECD average. We show both, along with the critiques.
Weigh the evidence →
06Secondary
The best path gates on understanding, not on the calendar.
Fraction knowledge at 10 predicts algebra at 16. Ages 9–12 look like the highest-payoff window. Calendar-based "algebra for all" has not raised achievement in two large studies.
The optimal path →