Creative thinking skills are needed in the 21st century learning. According to the P21 platform (Partnership for 21st
century learning), someone will survive in the 21st century if they have some skills of one of them is creative thinking skill. By
applying Research Based Learning (RBL), 64 students were given a problem namely Rainbow Connection. Through qualitative
research, student results are analyzed to know the level of their creative thinking skills. The results shows that the data of
students's creative thinking level are as follows: (i) In class A, 28 students have creative thinking skills of level 4, 2 students have
creative thinking skills of level 3, and 4 students have creative thinking skills of level 2. (ii) In class B, 20 students have creative
thinking skills of level 4, 2 students have creative thinking skills of level 3, and 8 students have creative thinking skills of level 2.
It can be concluded that the level of students creative thinking skills in solving Rainbow Connection problems through RBL are
relatively high.