We compared alternative instructional strategies for integrating knowledge of decimal place value and regrouping concepts with procedures for adding and subtracting decimals. The first condition was based on recent research suggesting that conceptual and procedural knowledge develop in an iterative, hand over hand fashion. In this iterative condition, conceptual and procedural lessons were interleaved. The second condition followed the common ordering of conceptual lessons before procedural lesson (concepts-first condition). All lessons were presented via a computer-based intelligent tutoring system and 72 sixth-grade students participated. Students in the iterative condition made greater improvements in procedural knowledge and comparable improvements in conceptual knowledge, compared to the concepts-first condition. Students in both groups did better when problems were presented in money contexts rather than symbolically. Both the iterative ordering of lessons and presenting problems in money contexts reduced students' digit alignment errors when adding and subtracting decimals. (Author)