8   DOUBLE TAP TO ZOOM WITH PHONE OR TABLET Chapter 1 Teachers have noted that facilitating a high level of collaboration and cre- ativity in early childhood environments can be very complicated. In particular, teachers of toddlers and young preschoolers noticed a conspicuous absence of students their age in the canon of project-based curriculum. In fact, in their book, Katz and Chard (2000, 17) are frank: “As we use the term, we imply a level of initiative and responsibility on the part of the children that would be difficult with most groups of children under three years old.” They were not alone in this view. Toddlers, in the eyes of many twentieth-century developmental theorists, were still largely waiting for the ability to hypothesize, not to mention negotiate, collaborate, sequence, and categorize. Although there were a few important exceptions (Edwards and LeeKeenan 1992; Musatti and Mayer 2001), most of the dialogue about and development of project-based cur- riculum centered around four- and five-year-olds. Who Are Toddlers? The definition and ideas of infancy, toddlerhood, and childhood have been the subject of much discussion, debate, and revision in the last two decades. The trend in recent years has been toward separating stages of early childhood into smaller substages, each with unique attributes and needs (Mangione, Lally, and Singer 1990): •• •• •• •• infants: birth to eight months mobile infants: eight to eighteen months toddlers: eighteen to thirty-six months preschoolers: thirty-six to sixty months This book focuses on toddlerhood and the months before and after—from the beginnings of mobility and language, around ten to fourteen months, to the early preschool period, thirty-eight to forty months. Educators consider toddlerhood a unique stage because in each area of development—motor, cognition, language, social, emotional—toddlers differ from (but also overlap with) both infants and older preschoolers. Major theo- rists of child development, such as Jean Piaget and Lev Vygotsky, have defined key elements of toddlerhood. COPYRIGHTED MATERIAL