The instructional models that have been implemented in the classroom could not support the development of students’ critical thinking skills. These instructional models can be well implemented if those models can facilitate students with meaningful learning experiences such as reading, connecting prior knowledge to new information being learned in the classroom as well as doing investigation-based activities, discussion activities, and evaluation activities. The authors conducted the research to develop a ReCODE (Reading, Connecting, Observing, Discussing, Evaluating) instructional model and valid, practical, and effective tools. The procedures for developing the model included the preliminary research phase, prototyping phase, and assessment phase. Data on the validity of the model were collected using expert validation instruments, while the practicality of the model was measured using the instruments for the model’s component practicality and the model’s implementation. The effectiveness of the model was examined using the critical thinking test and questionnaires. The model was implemented to first-year students from the Department of Biology Education, Universitas Negeri Makassar, in the even semester of 2018/2019. The results showed that ReCODE was (1) valid, in terms of the theory underlying the development of the model, the components of the model, and the instructional tools accompanying the model, (2) practical because it had feasible components, and the learning process could be carried out successfully, and (3) effective in improving student critical thinking skills; the model also received positive responses from the lecturer and the students. Thus, this study’s findings suggest that the ReCODE instructional model can be applied in the classroom to facilitate critical thinking.