Developing instrument to increase students' geometry ability based on Van Hiele level integrated with Riau Malay culture
The purpose of this research is to develop Geometry teaching materials and geometry instruments that can be used to improve the ability of Geometry based on Van Hiele's cognitive level integrated with Malay Culture. The research design used in this research was Research and Development (R&amp;D) which consists of several stages, namely: potential and problems, material collection, product design, product validity, product trials, product revisions, and mass products. The subjects of this study were students of mathematics education department in the first semester consisting of 65 students. The Validity of Teaching Materials inform students work sheet was analyzed using the validation sheets of teaching materials proposed by Akbar (2013) and Practical Analysis was analyzed using the formula proposed by Riduan (2016). The test instrument was analyzed using Aiken's validity and interrater reliability. The questionnaire instrument was analyzed using Aiken's validity and interrater reliability. Data analysis shows that teaching materials are in the form of student worksheets in the valid and practical categories. The test instrument was developed in valid and reliable categories. The developed questionnaire instrument in the form of essays in a valid and reliable category. Teaching materials and instruments in the form of questionnaires and essays according to experts can be used to obtain relevant data and improve the ability of geometry based on the level of Van Hiele integrated with Malay Culture.