Six fifth-grade children participated in a four-day teaching experiment on complex additively structured problems to investigate difficulties in concurrently holding in mind situations in which items play multiple roles. Difficulties included distinguishing take-away difference from comparison difference and indirect evaluation of an additive…

Studied schemes involved in solving two-step arithmetic word problems in (n=1824) elementary schoolchildren in Israel. Compound schemes and combinations of operations were found to affect the difficulty level of the problems. Appendix includes two versions of the test instrument. (Contains 17 references.) (MKR)