Developing multiple representation’s teaching materials assisted by blended learning to enhance students’ critical thinking skills

Chemistry can be represented in three different levels, macroscopic, sub-microscopic, and symbolic. Those three levels of representations are integral in developing chemistry concept understanding. Nonetheless, there are still many teachers who only emphasize on macroscopic and symbolic representations resulting in students who do not fully understand the concept. Technological advances in the 21st century also affect the field of education. Learning that was originally only performed in a face-to-face manner can now be performed by means of internet assistance so that teachers and students do not have to face-to-face in doing learning (blended learning). Learning Management System in blended learning can be used as a medium to emphasize three representations of chemistry. 21st-century learning has been developed in relation to the skills that students have to acquire, one of which is critical thinking. The purpose of this research and development is to develop chemistry teaching material on electrolyte-nonelectrolyte solutions and colligative properties based on multiple representations assisted by blended learning to improve students’ critical thinking skills. The development model refers to Lee & Owens which has five steps, 1) assessment/analysis, 2) design, 3) development, 4) implementation, and 5) evaluation. The study was conducted on semester II science study program students. The materials selected were electrolyte-nonelectrolyte solutions and colligative properties. The validation of these materials was 73%. The results of the study showed that the teaching materials are valid and suitable for use. Teaching materials are effective in improving thinking skills as shown by the n-gain value of 0.40 (medium category).