Achieve launched this study to help inform the decisions states are making about high school assessments by providing greater insights into the world of college admissions and placement testing. Achieve analyzed more than 2,000 questions from college admissions and placement exams to determine how these tests compare to one another and how well…

This study examined the development of the rational number concept as a ratio. Preliminary to the description of the study is an introduction discussing constructivism and equilibration. The study itself tests whether equilibration theory holds, and if so, what is the nature of its "phases" and whether these are found at each of the "periods" of…