Prof. Joseph Novak (Cornell) developed conceptual maps based on David Ausubel's subsumption (aka meaningful learning) theory and Piaget's concept of conceptual schemes. Conceptual maps have been proven successful across all levels of education worldwide (check Google Scholar).

„Es gibt keine primitive Intuition der Gleichzeitigkeit.“

The move toward social constructivist pedagogical models, initiated by researchers such as Piaget and Vygotsky, makes the wiki a potentially useful educational tool. The wiki can provide the medium by which learners communicate and negotiate in their efforts to reach a shared understanding of a problem (Bruns, 2005).

this contradicts Piaget's view of universal stages and content of development.

Jean Piaget, John Dewey, Maria Montessori, or Paulo Friere

(Actually, I’m pretty sure the company above meant “constructivism” here, since “constructionism” builds upon the learn-by-doing of constructivism by stressing the importance of the tangible not just the abstract.)