In the light of continuous change of global perspectives, current educational contexts have been evolving to cover the necessary 21st century skills that the individuals must acquire. Two of the 4Cs (creativity, critical thinking, collaboration and communication) of the 21st century educational trends; creativity and creative thinking are the key characteristics of the learners. Considering as one of the requirements of the global communication, knowing and learning a foreign language should keep up with the current improvements in the field of education. Language learners should think critically and creatively in order to communicate with people to enhance the global collaboration. The purpose of this study is to enhance students' creative thinking skills through appropriate training and to understand the effectiveness of the stimuli type--visual or audio. A pre-experimental research design was chosen for the implementation of the training program. Two different groups--visual and audio--were given either visual or audio stimuli at the beginning of creative thinking tasks. 12 participants were chosen via convenience sampling for each group and the ages of the learners are between 12-13. The training continued for 6 weeks and the participants took 3 hours of training were week. Each training session covered creative thinking tasks which were adapted or designed for the development of creative thinking skills--fluency, flexibility, originality and elaboration. A task-based pretest was implemented before the treatment and the students' creative thinking skills were measured through figural, written and oral tests and the post-test was implemented to check the effectiveness of the training program. The results were scored by two different raters and the scores were analyzed through SPSS program. The results indicate that the creative thinking capacity of both groups has improved however the visual group students have higher creative thinking after the completion of the training program. This study suggests that although regarded as a higher level of reasoning, creative thinking can be enhanced to some extent among the secondary school learners of English and it should be a part of EFL curriculum as an essential learning skill. An earlier version of this article was presented in the 5th NTELT Istanbul Conference on March 30, 2018.