A blunt phrase Education Secretary Arne Duncan used to describe 15-year old American student’s performance against other nation’s students in the 2012 Program for International Student Assessment (PISA).  The test, conducted every three years, is designed to measure reading, mathematics, and science literacy as well as other cross-curricular competencies like problem solving.

Average US scores in mathematics literary ranked lower than 29 education systems and higher than 26 education systems.  Although science and reading literacy scores were above average for the US versus other nations, the average performance in each competency over time has not improved.

Source: http://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2014024