Fostering students’ mathematical critical thinking skills on number patterns through digital book STEM PjBL

21st-century learning requires students to have the competency problem-solving and critical thinking, creative thinking, collaboration and communication. However, the mathematical critical thinking skills of Indonesian junior high school students remain relatively low. Therefore, the study aims to develop a digital book STEM PjBL to foster the students’ mathematical critical thinking skills. To achieve this aim development and research of the Borg and Gall (Gall et al., 2007) model continued with the experimental research conducted using one group pre- and post-test design. Instrument tests of mathematical critical thinking skills and student perception questionnaires were employed to collect data. The findings indicate that the digital book STEM PjBL is valid and significant in fostering students’ critical thinking skills and has a positive impact on other 21st-century learning skills. Furthermore, the data shows that students are satisfied and interested in learning through active teaching and learning methods that incorporate ICT tools and STEM-PjBL aspects.