Is Piaget a Cognitivist or constructivist?

Jean Piaget is known as one of the first theorists in constructivism. His theories indicate that humans create knowledge through the interaction between their experiences and ideas.

What is the core of constructivism? What are the characteristics of constructivism? What is constructivism IR theory? What is the constructionist perspective? What are the characteristics of constructivist teaching? What are the principles of social constructivism? What is a constructivist pedagogical approach to learning? When did constructivism start and end? Why did constructivism emerge? Is Cognitivism the same as constructivism?