Piaget is one of the most influential educationalists of all time. His view on how children construct learning and seek equilibrium have had major impacts on education systems around the world.
Zibda: Children are innately curious about their surroundings and live life as "little scientists". Learning is constructed regardless of the type of instruction and connecting new learning to schema is a necessary part of learning. They go through distinct learning stages as they get older. His work came to the United States in the 1960's. The big idea is that according to Piaget,children want the world to make sense and maintain a sense of equilibrium.
Great video explaining the stages of development
Here are some videos about testing the different stages.
This slideshow is excellent and worth your
time if interested in the learning process
according to a cognitive view.