Our research project examined the effects of graphic calculators amongst ninth grade pupils from Arab society in the Negev area in Israel. The goal of this research was to discover and characterise the ways of thinking in this population about the concept of positivity and negativity of functions. To perform this investigation we compared two groups of pupils: the experimental group (n = 95) studied the topic by means of graphic calculators, while the control group (n = 89) studied the same topic in the traditional way. For the purpose of this research we developed a questionnaire based on the material studied in class, such that each question could be answered using either method. The pupils in the experimental group understood the concept of positivity and negativity of functions better than did the pupils of the control group. We found that the use of graphic calculators encourages the development of significant thinking. (Contains 10 tables and 1 figure.)