“…In line with these results, Cronbach's Alpha Aan Yuliyanto 1) , Turmudi 2) , Ernawulan Syaodih 3) , Arie Dharmawan 4) , Cahya Karisma Pertiwi 5) , Idat Muqodas 6) , Dadan Rusdiana Saputra 7) 74| Volume 9, No 1, June 2021 ≥ 0.7 is considered acceptable (Xie, Li, Roos, Fong, Lo, Yeo, Yang, Chong, & Thumboo, 2006). Instrument with a Cronbach's Alpha value> 0.7 is considered reliable and can be used for further research (Astutik & Priantono, 2020;Bolarinwa, 2015;Lima-Rodriguez, Lima-Serrano, & Dominguez-Sanchez, 2015;Tsang, Royse, & Terkawi, 2017;Wells, Russell, Haraoi, Bissonnette, & Ware, 2011). Thus, the mathematical creative thinking skills instrument can reveal student responses that are not much different when applied to similar students even though it is implemented at different times and places.…”