The effect of a model suggestion for the development of 21st century skills on some skills of secondary school students

21st-century skills are essential for students to learn as these skills bear the qualifications and competencies that an individual needs in every aspect of life. The purpose of this study is to design a model, ain accordance with the principles of cooperative learning and multiple intelligence theory, in which secondary school students' are expected to improve their 21st-century skills and to investigate the effectiveness of the model on these skills. Thus, this study explored the attitudes of secondary school students' 21st-century skills, scientific creativity, critical thinking, entrepreneurship and science and technology. This study was designed as action research because it aimed to improve available teaching processes. In the 2019-2020 academic year, nine male and 12 female 6th-grade students, and five male and 10 female 7th-grade students from Bayramyazı Secondary School in Kovancılar, Elazığ participated in this study. The total number of participants was 36. The duration of this study was 6 weeks. Both quantitative and qualitative data were collected. The quantitative data was collected through the 21st Century Skills Test, Scientific Creativity Test, Critical Thinking Test, Science Education Entrepreneurship Test, and Science and Technology Attitude Test. The qualitative data was collected through semi-structured interviews and students' diaries. While quantitative data analysis was conducted with the utilization of SPSS 23, qualitative data was analyzed through descriptive and content analysis methods. According to Wilcoxon signed-row test results, the designed learning model contributed to 6th- and 7th-grade students' 21st-century skill improvement. The application has contributed to the scientific creativity skills of the 6th and 7th grade students. It did not statistically affect the critical thinking skills of 6th grade students, but contributed to the development of 7th grade students' critical thinking skills. While there was no improvement in the entrepreneurship skills of the 6th grade students, it was effective in improving the entrepreneurship skills of the 7th grade students. It contributed to the attitudes of 6th grade students towards science, but it was not effective in improving 7th grade students' attitudes towards science. On the other hand, qualitative data analysis revealed that the participants liked the model, considered it enjoyable, and benefitted from the group work. In conclusion, collaborative multiple intelligence cycle model, which aimed to improve students' 21st-century skills, was effective is generally effective in improving some skills of secondary school students and implementing such a model during learning processes was important and necessary.