A task was developed to differentiate the reasoning of elementary school students in fifth, sixth, and seventh grades. Subjects completed 16 matrices containing two, three, or four dimensions and varying in the embeddedness of the dimensions. They also solved a formal operational task assessing ability to isolate, exclude, and include variables.…

This research hypothesized that preformal-operational children (before age 11) can improve their ability to write persuasive essays at an age earlier than Jean Piaget's developmental stage model would predict. A Vygotskian social interactionist approach, which claims that adult intervention can help children achieve what may have seemed beyond…