'Its size is really wood': The development of buoyancy and material kind understanding in children between three and seven years of age

Developments in buoyancy and material kind understanding were investigated. Material kinds are the "stuff" of which things are made (e.g. wood). Everyday, predictions and explanations of the physical world are based on knowledge and understanding of material kinds. When and in what ways do children utilize their developing understanding of material kinds to make judgments about the physical world? As children begin to realize that objects in the world are made of different kinds of "stuff", how do they make use of this knowledge? The answer to these questions have important implications for our understanding of the organization and development of children's scientific knowledge and the creation of science curriculum for elementary and preschool classrooms.;In three experiments, children between three and seven years of age participated in four different tasks; a buoyancy task, a material induction task, a material identification task, and a material naming task. In the buoyancy task, participants were asked to predict and explain which of a set of objects would sink or float. For the material induction task, our lab designed a machine that lit up and played a song when wooden objects were placed on it. Participants were asked to predict and explain which objects would turn on the machine. In the material kind naming and sorting tasks, participants were shown pairs of objects. They were asked if the objects were made of the "same kind of stuff" or "different kinds of stuff" and then asked to name what kind of "stuff" out of which the objects were made.;It was hypothesized and found that major developments in material kind and buoyancy understanding began around four years of age. Moreover, material consistent explanations and predictions on the buoyancy and induction task were related. It was hypothesized and shown that with age material kind and other relevant (e.g. weight) explanations were increasingly used to explain both buoyancy and a novel material property. It was hypothesized and found that increased performance on the material naming and identification tasks was related to increased performance and increased use of material kind explanations on the buoyancy and induction tasks.