Dynamic Models for Addition and Subtraction

One of the most important features of GeoGebra [1] is the coordination of the geometric and algebraic representations, easily observed in GeoGebra window. Using GeoGebra software the teacher can geometrically and fruitfully teach the concepts and algorithms of arithmetic operations in the elementary school. Our paper focuses on two important operations: addition and subtraction in the set of whole numbers. Using GeoGebra features [2], we visually demonstrate the concepts of these two operations and help the students to develop the process of mastering addition and subtraction facts. Our paper aims to achieve two objectives. Firstly, one objective is to teach addition and subtraction using dynamic models that are related to the concept of base ten blocks using 2D model: equal rectangles representing ones, the strips of 10 rectangles representing tens. Secondly, by creating dynamic models for teachers and students we want to: 1) increase teacher pedagogical content knowledge and improve the instructional practice; 2) promote student learning by improving teaching practices and providing capacity-building solutions; 3) encourage the teachers to engage themselves in research activity and innovative educational practices and teaching strategies.