Guiding children in learning subtraction by using contextual strategy: as an attempt to develop students' number sense

Subtraction operations are basic number operations that have been introduced to students at the 2^nd grade of elementary school. Several studies have shown that this topic is difficult for students to understand and causes many problems in learning of numbers. Students' constraints in performing this subtraction operation usually occur when subtracting two numbers in tens, hundreds, or more or numbers containing 0. One of the procedures that teachers often teach students in solving the problem of subtracting two numbers is borrowing techniques. This technique is often seen as forced and very abstract to students. This study aims to describe how students thinking in performing subtraction on numbers through more contextual strategies that they understand. This study used a single-subject research design with multiple baselines across individuals (n = 2) to evaluate the effectiveness of the measures performed. The intervention observed in this study was to use the number of subtraction technique with a different contextual strategy between the two subjects. The results indicate that the two contextual strategies used show a positive effect on understanding the number subtraction operation. The results also showed that subtraction without borrowing (not using formulas) made students more creative in solving the subtraction problem.