“…For example, significant differences among tenth-, eleventh-, and twelfth-grade students were not observed for their performance on combinatorial reasoning problems. Eckstein and Shemesh (1992) who found evidence supporting different functional dependence for problems of different reasoning modes have reported similar results. Furthermore, the present study confirms that the development and saturation of formal cognitive abilities is not complete even for twelfth-grade students (Lawson, 1985;Renner & Stafford, 1972;Shayer, Kucherman, & Wylam, 1976;Valanides, 1997a) and that a high percentage of higher secondary school students are apt to be transitional (Karplus et al, 1980;Zeidler, 1985) or even concrete reasoners (Valanides, 1997b).…”