Abstract:
The purpose of this research was to study misconceptions about Numbers of seventh grade students in schools under Ratchaburi Educational Service Area Office 1. The population of this research were seventh grade students in schools under Ratchaburi Education service area office 1. The samples were 402 students in academic year 2009. The research instrument was written mathematics test on Numbers constructed by the researcher with the reliability of 0.76. The interview on Numbers misconceptions was also conducted. The data were analyzed by means of arithmetic means, standard deviation, and percentage. The results of this research revealed that misconceptions categories were ranked from highest to lowest as below. 1) Distortion of theorem, law, formula, definition, and property: most of students misunderstood about basic theorem, law, formula, definition, and property. Consecutively, students memorized basic theorem, law, formula, definition, and property wrongly. 2) No verification of solutions: most of students worked correctly on mathematical procedures, but they could not find the right answers. Consecutively, students used wrong mathematical procedures, but they could find the right answers. 3) Technical Error: the misconception was the careless calculations. 4) Data Misusing: most of students did not work for relevant or wanted answers. Consecutively, students neglected some necessary data for solving problems. 5) Misinterpretation of question: the students could not translate verbal sentences into mathematical sentences