The 4Cs are skills that emphasize learning across the 21st century (Critical thinking, Communication, Collaboration, Creativity). Problem-solving, one of the 21st century's skills, developed by implementing PjBL-STEM learning models. PjBL-STEM learning focuses on developing students' ability to be more engaged, innovative, and open to the idea of concepts learnt through project-based activities that incorporate STEM aspects in real life. The study's goal is to examine how PjBL-STEM learning improves problem-solving skills. The research method used was quantitative research through a one-group pre-experimental design with pretest and posttest. A total of 35 students from class XI IPA 2, SMA X Muhammadiyah Surabaya, participated in the study.  This study uses purposive sampling to consider students' abilities and conditions of delivery of subject matter. The study's results (N-gain) were 0.59, classified as "medium".  According to the findings of this study, Learning the PjBL-STEM model has been sufficient for enhancing problem-solving abilities in dynamic fluid materials. The characteristics of the PjBL-STEM learning model that focuses on the 'student-centred model' significantly influence problem-solving skills. The advantages of this model should be accompanied by improvement of educational facilities and teaching skills in the learning process in order to create a balanced learning environment

Learning media was used to explain the theory and minimize misconceptions. 50% of physics teachers in East Java have difficulty creating learning media of circular motion. Therefore, researchers created an innovation learning media and analyze the perception of physics teachers to Arduino-based "Rotating Wheel" learning media (ABRW). This research used R&D design with a 4-D model. The subjects were 24 physics teachers throughout East Java and 35 students's XII MA Jabal Noer, Sidoarjo. The instruments used the form of teacher and student response questionnaires and material expert validation sheets. The data analysis is the calculation of the average value of validation results. The result from the physics teacher's and student response more than 65.8% and 75% in very positive category and validation more than 85% with a very valid categori. Thus, it was concluded ABRW props are feasible to use as well as learning physics in a circular motion topic.

The purpose of this study was to analyze the scope related to the subject of problem-solving skills based on multiple representation in 2016 – 2020 with 20 documents through bibliometric analysis. The research method used was a literature study through all the articles analyzed in this study. The articles were taken from the Scopus database with sampling in 2003 – 2020, resulting in 29 scientific work data exported in *.ris (RIS) and *CVS formats. Then, those data were processed using VOSviewer and Microsoft Excel. The results of publications in the last five years have increased. Indonesia is the dominant country in publicizing papers about this topic. Institutions from Germany managed to publish most of the documents about multi representation. Meanwhile, Poland is the origin country of the authors with most publications. The visualization of research trends on multi representation resulted in four main clusters: (1) multi representation related to students, representation, and learning processes (2) multi representation as a class (3) multi representation related to the problem (4) multi representation as a model and process. Meanwhile, Indonesian researchers are very active in contributing to this topic, in line with the number of publications by country, namely Indonesia.

This study aims to analyze research trends related to PjBL-STEM topics in 2016-2020 through bibliometric analysis with the Scopus database. Based on the criteria, it obtained 1,169 documents. Microsoft Excel was used to analyze data and VOS viewer as a data visualization. The results showed that PjBL-STEM research is increasing every year. The USA contributes the most research in the world, Indonesia ranks second. Universitas Pendidikan Indonesia, Universitas Negeri Malang, Universitas Sebelas Maret, and Universitas Negeri Semarang are among the top affiliates in PjBL-STEM research in the world. Visualizing the trend of PjBL-STEM research in 2016-2020, there are three clusters, namely 1.) PjBL-STEM as a framework, 2.) PjBL-STEM as self-development, and 3.) Effects of PjBL-STEM research. The results of this study can help researchers related to PjBL-STEM research trends in the world and provide direction in further research.

The quality of education can be improved by developing learning methods, curriculum development, and learning media development. One of them is learning media in the form of comics. This research aims to develop physics comics and analyze the validity of learning media of physics comics on the historical material of atomic development.  The research was conducted using the R&D research model (Research and Development) with the 4-D model (Define-Design-Develop-Disseminate). Based on the stages, obtained learning media products that were declared eligible after validation by two high school physics teachers and an expert lecturer gained the average validity in the media component of 90.0%, the display of 89.2%, the material by 90.7%, and the language by 95.4%. In general, the student's responses to the use of physical comic learning media include comic physics can increase motivation in learning (88.6%), students prefer that physics learning uses comic media (88.9%), through comic media, students are introduced to atomic inventors (88.9%), and physics comics can help to understand the historical material of atomic development (83.3%). Based on the study results, learning media of physics comics on the historical material of atomic development deserves to be used in physics. The implication of this study can help other researchers as a reference related to the development of comic physics learning media.