“…Children show some understanding of logical necessity, consistency, and impossibility beginning about age 6 (Ruffman, 1999;Somerville, Hadkinson, & Greenberg, 1979;Tunmer, Nesdale, & Pratt, 1983). Research also shows continuing development in the comprehension of necessity, possibility, suffi ciency, indeterminacy, and associated concepts over the remaining years of childhood (Byrnes & Beilin, 1991;Morris & Sloutsky, 2001;Piaget, 1987;Pieraut-Le Bonniec, 1980;Ricco, 1997;Ricco, McCollum, & Wang, 1997), and age-related constraints on the ability to learn such concepts (Klahr & Chen, 2003).…”