... The draft materials were revised on the basis of the evaluation studies and teacher feedback, and were commercially published. Finally, extensive summative evaluations of the published materials were carried out by UCSMP and by a group at Northwestern University, often focusing on issues identified as problematic during the field test (Arron, 1993; Carroll, 2000a Carroll, , 2000b Carroll, , 1999 Carroll, , 1998a Carroll, , 1998b Carroll, , 1997 Carroll, , 1996b Carroll, , 1996c Carroll, , 1996d Carroll, , 1995a Carroll, , 1993 Carroll & Fuson, 1998a, 1998b Carroll, Fuson, & Diamond, 2000; Carroll & Isaacs, in press; Carroll & Porter, 1998 Ding, 1997; Drueck, 1996; Drueck, Fuson, Carroll, & Bell, 1995; Fraivillig, 2001 Fraivillig, , 1996 Fraivillig, Murphy, & Fuson, 1999; Fuson, 1997; Fuson & Carroll, 1998; Fuson, Carroll, & Drueck, 2000; Fuson, Carroll, & Landis, 1996; Murphy, 1998). Because of this elaborate development process, the production of the first edition of EM took more than 10 years. ...