You can download a pdf version of this article at https://eric.ed.gov/?id=ED603587. Please note that this web version was updated later with the following reference added. Biancarosa, Gina, Anthony S. Bryk, and Emily R. Dexter. “Assessing the Value-Added Effects of Literacy Collaborative Professional Development on Student Learning.” Elementary School Journal 111, no. 1 (September 2010): 7–34. https://doi.org/10.1086/653468. INTRODUCTION Return on investment (ROI) is a concept that originated in the business world in the early twentieth century. According to the Hagley Museum and Library, the concept and the formula were first developed in 1914 by Donaldson Brown, the Assistant Treasurer of the […]