Effects of external reinforcement and cognitive conflict-based treatments on students' acquisition of ability to control variables at an early age were studied. Smedslund's finding was confirmed. Nearly half of trained students with a mean age of 11.8 years could be classified in late formal operations. (CC)

Reports on misconceptions held by intermediate grade students concerning chemistry textbook concepts, on the relation of reasoning ability to those misconceptions, and on the extent that textbooks encourage misconceptions. Concludes that the level of understanding displayed for the selected concepts, in combination with the nature of students'…