Educators know American students are struggling with math, but it's sobering to realize the depths of their struggles, compared to students in the rest of the world.

The Organization for Economic Cooperation and Development’s Programme for International Student Assessment found that the United States ranks significantly below average in mathematics comprehension, accounting for only 8.8% of all top-level mathematics performers at the K-12 level.

Forbes Contributor James Marshall Crotty decided to examine why in a two-part series. One of the reasons, he suggests, is lack of parent engagement. 

"In the U.S., the average parent is not so engaged. And the results speak to that indifference," he wrote. "According to the National Math+Science Initiative, only 36% of U.S. high school students entering college are prepared for university-level mathematics."

Crotty also wrote that some analysts believe socioeconomic status plays a large role in math deficiencies. 

Olin College of Engineering Associate Professor Sanjoy Mahajan doesn’t agree.

“If poverty explained the U.S.’s poor performance, with scores of the bottom quartile dragging down and obscuring the alleged great performance of the U.S. top quartile, then the U.S. top quartile should do well internationally,” wrote Mahajan. “However, when compared against the top quartiles in other countries, the U.S. rank drops from 26th to 32nd. Similarly, U.S. students with [socio-economic status] at the OECD average do slightly worse than the U.S. average.”

Read Crotty's full story here.