The Construction of Mathematics Diagnostic Test on Factoring A Second of Poly Nomials for Eighth Grade Students in Samutsakhon

Abstract

The objectives of this research were 1) to construct a mathematics diagnostic test on second degree polynomial factorization for grade 8 students in schools in Samutsakorn province, 2) to validate the content validity, the difficulty, the discrimination and the reliability of the test, and 3) to create a diagnostic test manual for learning mathematics and how to find the cut-off points. 4) to diagnose the deficiencies of the learner. The sample consisted of 900 students who were selected by technique from grade 8 students in Samutsakhon. The research instruments was a set of 70 mathematic diagnostic test questions requiring the students the choose their best answer among 4 choices. The results of this research were the content validity of the mathematic diagnostic test  was ranged from 0.80-1.00; the difficulty index of each item ranged  was from 0.41-0.72 , the discrimination index calculated by Brenham method was ranged from 0.50-0.80, and the reliability of precision calculated by Livingston valuable equal to 0.97. The cutting score using Angoff’s method was 41 points from 70 points. The diagnostic results found that the topics students misunderstood the most were the topics on factorization of two degree poly nomials that are squared as were as factorization of the second degree poly nomial that is completely square.