Due to the COVID-19 pandemic, learning activities have encountered obstacles. One of the impacts was the low learning outcomes achieved by students. The purpose of this study was to improve the learning outcomes of junior high school students during the physical distancing period by implementing problem-based learning through Smart Apps Creator 3. This Classroom Action Research (CAR) used Smart Apps Creator 3 as the platform during learning activities of junior high school students. The research subjects were junior high school students (VIII graders of SMP Negeri 8 Surakarta) with a total number of students was 32 which consisted of 16 males and 16 females. The results showed that the application of Smart Apps Creator 3 has improved students’ learning outcomes. It has been proven that the average test score increased from 73.43 (pre-cycle) to 85.56 (cycle II). Moreover, the N gain score obtained was 0.45 (categorized as sufficient). In addition, the percentages of classical learning completeness were 59.37% (pre-cycle) and 93.75% (cycle II). Thus, the Smart Apps Creator 3 can improve student learning outcomes.

This research is a qualitative descriptive research with the aim to describe students' ability in construct critical thinking. The subjects of the study were the students of SMP Negeri 8 Surakarta city for the academic year 2019/2020 which amounted to 762 students, with a sample size of 200 students . Population choose random sample of each class. Instrument used consisted of test the critical thinking skills of students through a questionnaire with 20 statements questionnaire number . The questionnaire sheet was developed based on 6 indicators that were the focus of the study. The indicator in question is a discussion that is able to ask questions, answer questions, solve problems, make conclusions, question and assess the results of observations . The results showed that if seen from the average level of student achievement on each indicator, the average achievement on the indicator analyzing argument is 72,28%, on the indicator of asking ability is 78,55%, on the indicator answering questions is 78,35%, on the indicator of solving the problem is 61,95%, the indicator makes a conclusion is 55,45%, and the indicator of the skill of evaluating and evaluating the results of observations is 72.50%. The results also showed that in general students of SMP Negeri 8 Surakarta had critical thinking skills with quite critical criteria, with 8 students classified as very non critical (4%), who were classified as non-critical were 47 students (23,5%), who were classified as as quite critical were 133 students (66,5%), who were classified as critical were 10 students (5%), and those classified as very critical were 2 students (1%). This proves that students' critical thinking skills still need to be trained further in order to be improved.