Relational Thinking
In their study, “The algebraic nature of students’ numerical manipulation in the New Zealand Numeracy Project”, Irwin and Britt (2005) argue that the methods of compensating and equivalence that some students use in solving number sentences may provide a foundation for algebraic thinking (p. 169). These authors give as an example the number sentence 47 + 25 which can be transformed into 50 + 22 by “adding 3” to 47 and “subtracting 3” from 25. They claim (p. 171) “that when students apply this strategy to sensibly solve different numerical problems they disclose an understanding of the relationships of the numbers involved. They show, without recourse to literal symbols, that the strategy is generalizable.” Several authors, including Stephens (2006) and Carpenter and Franke (2001), refer to the thinking underpinning this kind of strategy as relational thinking.