The principle of "inversion," that a + b - b "must" equal a, is a fundamental property of arithmetic, but many children fail to apply it in symbolic contexts through 10 years of age. We explore three hypotheses relating to the use of inversion that stem from a model proposed by Siegler and Araya (2005). Hypothesis 1 is that…

Specific criteria for the rating of each questionnaire item are explained in detail. The teacher is asked, after reading the questions carefully, to assign each first grade student a rating for every question. This rating should be based on a personal knowledge of the student. The booklet is divided into three sections w1th section 1 focusing on…