WASHINGTON — As the school year begins, here are some facts about education in America:

How many students?The National Center for Education Statistics estimated that in 2013, 50.1 million children will be enrolled in U.S. public schools, and 5.2 million will be in private schools.That doesn’t include students who are home-schooled. NCES, the Education Department’s statistics arm, also estimated there were 1.5 million U.S. students home-schooled in 2007.Enrollment in colleges and universities was estimated to reach a record 21.8 million this fall, according to NCES.

Who’s teaching them?There are about 3.3 million elementary and secondary public teachers in 2013, leading to a student teacher ratio of 15-to-1, NCES said.The average teacher in a public school earned about $56,000 for the school year that ended in 2011, according to the agency.

Spending on kids?Teacher salaries are just part of the total spent on educating children. All told, NCES says $591 billion will be spent during the new school year. That breaks down to an average $11,810 for each student.

What are they taught?The buzz word these days is Common Core. The Common Core State Standards establish benchmarks for student learning in math and reading.Forty-five states and the District of Columbia have adopted the standards, which critics decry as tantamount to a national curriculum.Supporters counter that the standards are necessary to ensure that high school graduates are ready for college or career.

How safe are students?More than 1.2 million students between ages 12 and 18 were victims of crimes at school in 2011, according to NCES and the Bureau of Justice Statistics. Of those, nearly half were violent crimes and 648,600 involved thefts, the agencies said.Among students ages 5 to 18, there were 11 homicides and three suicides at school from July 1, 2010, to June 30, 2011.