“About 70 percent of middle grades students in the United States exhibit misconceptions, but nearly none of the international students in Korea and China have a misunderstanding about the equal sign, and Turkish students exhibited far less incidence of the misconception than the U.S. students,” note Robert M. Capraro and Mary Capraro of the Department of Teaching, Learning, and Culture at Texas A&M."
My first thought was that maybe this was too much fuss about nothing. They are talking about young people who confuse the equal sign as an operator, sort of ...2 + 5 = ...
But it seems that the mis-conception is restrictive on future math success.
"They have been trying to evaluate the success of math education through students’ interpretation of the equal sign. They have published several articles on this topic, with the most recent one published in the February 2010 issue of the journal Psychological Reports.
Students who exhibit the correct understanding of the equal sign show the greatest achievement in mathematics and persist in fields that require mathematics proficiency like engineering, according to their research."
Here is a Video about the report.
ADDENDUM: I found a link to some material from authors about a comparison between US and Chinese texts here