Environmental learning in the 21st century requires students to have Higher Order Thinking Skills (HOTS). The purpose of this study was to measure HOTS students using Higher Order Thinking Skills Assessment based on Environmental Problem (HOTS-AEP). The research method used in this study was descriptive method with a total sample of 248 students consisting of Elementary School (ES), Junior High School (JHS), Bachelor Program (BP), and Master Program (MP). The results showed that students overall have a very low HOTS category. HOTS scores scale of 0-100 on ES (22.3) are still higher than JHS (20.2). Whereas at the university level, BP scores (19.9) are lower than MP (21.4). This showed that learning must be oriented towards increasing HOTS through various media development learning, learning materials, learning models, and strategies. This study concludes that the HOTS score of students was still very low and needs to be improved.

Environmental learning in the 21st century requires a high level of thinking ability, especially to solve environmental problems when COVID-19 pandemic. This was to develop a new level of thinking, namely Higher Order Thinking Skills of Environmental Problem (HOTSEP) which is a revision of Anderson's Taxonomy. The purpose of this study was to measure students HOTSEP in the context of environmental problems related to COVID-19. The research method used in this research was descriptive. The sample used 277 university students from several cities in Indonesia. The instrument used HOTSEP which has 3 categories of thinking level start from develop innovation about environment (C6), solve environmental problem (C5), criticize environmental problem (C4). The results showed that students HOTSEP were still in the very low category (33.64). This study concludes that the HOTSEP of students was still low and needs to be improved to the understanding of COVID-19 concept in environmental learning. Suggestion for further research was HOTSEP need to implement in school or university for several environmental learning topics in many subjects/courses start from Natural Science, Social Science, Engineering, and others relevant subject. HOTSEP can be measured not only in school or university, HOTSEP can be implement in community and public.

Diagnostic tests are generally two or three-tier and based on classical test theory. In this research, the Four-Tier Diagnostic Test (FTDT) was developed based on modern test theory to determine understanding of physics levels: scientific conception (SC), lack of knowledge (LK), misconception (MSC), false negatives (FN), and false positives (FP). The goals of the FTDT are to (a) find FTDT constructs, (b) test the quality of the FTDT, and (c) describe students' conceptual understanding of physics. The development process was conducted in the planning, testing, and measurement phases. The FTDT consists of four-layer multiple-choice with 100 items tested on 700 high school students in Yogyakarta. According to the partial credit models (PCM), the student's responses are in the form of eight categories of polytomous data. The results of the study show that (a) FTDT is built on the aspects of translation, interpretation, extrapolation, and explanation, with each aspect consisting of 25 items with five anchor items; (b) FTDT is valid with an Aiken's V value in the range of 0.85-0.94, and the items fit PCM with Infit Mean Square (INFIT MNSQ) of 0.77-1.30, item difficulty index of 0.12-0.38, and the reliability coefficient of Cronbach's alpha FTDT is 0.9; (c) the percentage of conceptual understanding of physics from large to small is LK type 2 (LK2), FP, LK type 1 (LK1), FN, LK type 3 (LK3), SC, LK type 4 (LK4), and MSC. The percentage sequence of MSC based on the successive material is momentum, Newton's law, particle dynamics, harmonic motion, work, and energy. In addition, failure to understand the concept sequentially is due to Newton's law, particle dynamics, work and energy, momentum, and harmonic motion.