As national and international assessments continue to show students struggle with rational concepts, which are seen as a major stumbling block for future career in STEM fields, we used the certainty of response index (CRI) as a method of analysis to investigate a group of 40 United Arab Emirates (UAE) seventh grade students' understanding of basic fraction concepts. The types of errors and misconceptions displayed by students show that over 60% of all participants assumed that adding fractions procedurally is the same as adding whole numbers with many not being able to distinguish a numerator from a denominator. The results lead us to believe that the manner in which students were taught did not ensure the necessary transitional shift from learning whole numbers to learning rational numbers. Applying the theories of Dienes (1960) and Bruner (1966), we propose a method of teaching addition and subtraction of fractions that will allow students to build their own understanding of the rules using the graphing calculator as the medium for concept formation.