One of the causes of the low critical thinking skills of participants is caused by the learning process that focuses on mastering concepts alone without involving students to construct knowledge independently. Less comprehensive learning tools are the main obstacles that are often encountered in the implementation of learning. Project based learning is a constructivist method that is able to involve students to construct knowledge empirically, one of which is by utilizing the content of ethnoscience as a contextual approach in project learning. This study aims to develop a quality ethnoscience-based Project based learning devices in terms of content validity and empirical validity. This study uses the research and development method with the ADDIE model. The research was conducted at SMA Negeri 1 Gandapura. The research instrument used a validation sheet, student response questionnaires and teacher response questionnaires. Data analysis used the Aiken V coefficient for critical thinking skills test questions; Interclass correlation coefficient for lesson plans, Student Worksheets and Handouts; percentage formula for teacher and student response questionnaires. The results showed that the ethnoscience-based Project based learning devices were categorized as very feasible and could improve the critical thinking skills of students with an N-gain of 0.88 which was classified as high, and received a positive response from the teacher with a percentage of 96.71% and students by 86.35%

This study investigates the adsorption capacity of activated charcoal immobilized yarn against the methylene blue. Activated charcoal from refillable water filtration was used as a comparison. Activated charcoal was prepared by open and closed pyrolysis using a muffle furnace. The characterization of activated charcoal includes water content, adsorption of methylene blue, observations using a stereo microscope and Scanning Electrone Microscope. The results revieled that a 100 mesh activated charcoal powder with 75% Polyvinyl Acetate showed better properties in terms of thickness of the yarn layer, stability, and the surface morphology. The adsorption capacity test for the effect of the optimum time shows that activated charcoal from refilled water was optimum at 12 minutes, while activated charcoal regeneration, closed pyrolysis, and open pyrolysis took 9 minutes. The concentration of 1, 2, 3, and 4 ppm showed the absorbance results directly proportional to the increase in concentration. The greater the concentration, the higher the percentage of adsorption capacity. The comparative test for the type of activated charcoal with the best capacity is activated charcoal refill, regeneration, open pyrolysis, and closed pyrolysis, respectively. Based on the study results, it can be concluded that the immobilized activated charcoal yarn with 75% adhesive and 100 mesh activated charcoal powder can be effectively used to adsorb methylene blue, and open pyrolysis activated charcoal immobilized yarn can be regenerated