1.) Briefly describe the conservation-of-liquids experiments. What do these experiments tell us about a child''s cognitive abilities at the preoperational period and at the period of concrete operations? 2.) Briefly describe Piaget''s concept of egocentrism, distinguish between egocentric speech and thought. Also, at what developmental period is this form of thinking dominant? 3.) Briefly describe Piaget''s idea of object permanence. What is the general developmental sequence of object permanence and at what developmental period/stage do children acquire object permanence? 4.) Describe Vygotsky''s idea of tools and the idea of sign (symbol)? How are these two concepts related? How do tools become appropriated or internalized? 5.) Describe Vygotsky''s idea of egocentric speech and inner speech?