Maarten Dolk is a Dutch designer and researcher of mathematics education. Dr. Dolk is the CEO of New Perspectives Online and works on the development of the New Perspectives Online platform. Over the past 25 years, he has been associated with the Freudenthal Institute in the Netherlands, where he has been involved in the development of in-service materials for teachers and of multimedia learning environments for student teachers. Presently, he is involved in mathematics education projects in the Netherlands and Indonesia. Maarten is co-author of the first three books in the Young Mathematicians at Work series; he also coauthored two of the early childhood Contexts for Learning Mathematics units.