In an article featured in the Chicago Tribune and Seattle Times "Persuading girls to count on math," journalist Heidi Stevens highlights a recently published paper in the May/June 2011 issue of Child Development where scientists Dario Cvencek, Andrew Meltzoff, and Anthony Greenwald demonstrated "Children express the stereotype “math is for boys, not for girls” as early as second grade."
Persuading girls to count on math, By Heidi Stevens, Chicago Tribune & Seattle Times, May 17, 2011. Also see, e! Science News, March 14, 2011.
Cvencek, D., Meltzoff, A. N., & Greenwald, A.G. (2011). Math–Gender Stereotypes in Elementary School Children, Child Development, 82, 766-779.