Not sure you can link to Education Week without a subscription, but article entitled ??What Works? Reviewers Find No Learning Edge for Leading Math Texts? states:

?As the federal What Works Clearinghouse rolls out long-awaited ratings on the effectiveness of math programs for the elementary grades, one trend is becoming clear: Most major commercial textbooks can?t yet muster the proof that they are any better than their competitors at improving student achievement.
Of four reviews published by the online clearinghouse since September, only one elementary school math program has received even a qualified nod from evaluators for its research record.
Yet while publishers and textbook evaluators are concerned about the message those lukewarm effectiveness ratings may send, they also say the ratings may have more to do with the clearinghouse?s strict reporting system than with the programs themselves.
The What Works site says a handful of rigorously conducted experiments show that Everyday Mathematics, published by Wright Group/McGraw-Hill of DeSoto, Texas, has ?potentially positive effects? on achievement compared with more traditional math programs.?

According to the article, 19.2 percent of the U.S. market share for math textbooks goes to Everyday Mathematics. Remember the video I posted last week? After reviewing this video, a lot of folks may question the ratings of this report, but not for the same reasons as the textbook publishers. Some children might learn with Everyday Mathematics,  I just would not want my child to be taught with this book.