The sample of students in the 3rd prizes in schools under the jurisdiction of the Chanthaburi District 2 was derived by random multistage number 800 was used in this study was designed to measure the ability to think. judgment For Grade 3 48 items measured by the quality inspection checks the aesthetic content validity. With the way for the IOC. Check the difficulty and discrimination. Check validity using confirmatory factor analysis and determine the validity of the method of calculating the correlation coefficient ditch rider - Richard Johnson, 20.