نشریه پژوهش در آموزش شیمی
سال ششم شماره 1 (پیاپی 21، بهار 1403)

Chemistry, as one of the branches of basic science, plays an important and fundamental role in the development of technology, industries, and daily lives of human beings. It is crystal clear that in order to acquire the necessary concepts and skills in various fields of chemistry, chemistry education should be carried out both theoretically and practically. There is consensus of opinions in accepting this issue, and almost all chemistry professors and teachers collectively agree on this matter. However, to what extent is the practical teaching of chemistry in high school realized in practice? In this short discussion, a brief look at the necessary mechanisms for teaching chemistry practically at high school level is discussed. From theoretical aspect, various topics such as chemical theories, atomic structure, chemical bonds, balances and chemical reactions, and acid-base concepts are taught. One procedure for successful teaching of chemistry theories at high schools is the use of chemical models, animation, 3D images, simulations of reactions and chemical concepts. Although the mentioned methods can be effective in conveying chemical concepts and easier understanding of chemical principles, they may not be sufficient by themselves. Since practical skills and experience play a very important role in understanding and consolidating theoretical concepts, it is necessary for students to be placed in a real laboratory environment and to do practical projects in addition to various other experiments. In addition to its many benefits in helping learning, taking a test boosts students' self-confidence. For example, students believe that they can synthesize or produce a substance. Moreover, it may motivate them to study and conduct more research regarding chemistry-related businesses.

Today, with the non-stop progress of science and awareness, the use of creative teaching methods in various subjects, especially basic science subjects, has gained particular significance. The main goal of this research is to increase students' learning and interest by using the teaching method of scientific demonstration in the topic of covalent bonds from the chemistry book of 10th grade which has many basic contents and concepts that require skill, experience, and knowledge requiring efficient and appropriate teaching method. The population of this study was the 10th grade students studying experimental and math-physics at Miyad, Farzanegan, and Hazrat Fatemeh Al-Zahra High School in Rabat Karim, and it used descriptive quasi-experimental method. In this research, students' understanding of theoretical and scientific concepts, such as sharing of valence electrons and formation of covalent bonds was initially investigated, and their misconceptions of scientific concepts were extracted. Then, while studying and gathering information from up-to-date scientific sources and using the experiences of experienced teachers in the meetings of the educational groups and the school council, and of course, changing the methods by adding the seasoning of creativity, covalent bonds were taught using a scientific demonstration. The effectiveness of this method can be verified through field-based data collection methods such as a Likert scale questionnaire. The results of this research showed that scientific demonstration was an exciting method for the students and provided an opportunity to learn chemistry along with play and fun so that their learning motivation and interest in the lesson can be enhanced.

The purpose of this research is to investigate the effect of combined teaching with the laboratory rotation model on students' learning in the concept of balance. The study used a quasi-experimental method with two control and experimental groups. The population included all students of the technical and vocational branches of Najafabad are studying during the academic year of 2023-2024. A total number of 35 students were selected through convenience sampling and were trained in two groups of 15 and 20 students using combined and traditional teaching methods. In the experimental group, the combined method with the laboratory rotation approach was implemented to teach the concept of balance, and the control group was trained in the usual way. To measure the learning rate of the two groups, a researcher-made test was administered. The reliability of this tool in Cronbach's alpha was 0.75, and its validity was checked using the content validity method. After ensuring the homogeneity of the variances and the normality of the scores, one-variable covariance analysis method was used to test the research hypothesis. The results of this research showed that combined teaching with the laboratory rotation approach has a positive and significant effect (P<0.05) on students' learning in four aspects of the concept of balance, including the calculation of the ratio of coefficients (with the effect of 0.187), the coefficient (with the effect of 0.172), the law of mass conservation (with the effect of 0.266), and the using of natural numbers (with the effect of 0.350). Considering that combined education with laboratory rotation approach brings special possibilities in some cases such as access to resources, communication between teacher and learner, doing and presenting assignments for students, this type of learning leads to higher learning. Therefore, it is recommended for teachers to use the features of this educational approach to teaching-learning experiences to enhance students' learning.

The production reaction of iron from iron (III) oxide (hematite, Fe2O3) in industry is carried out by burning a mixture of hematite/carbon at high temperatures. Typically, in schools and student research laboratories, this experiment is conducted using the wood-sulfur method, where sulfur-coated wood sticks are immersed in the Fe2O3/Na2CO3 mixture and then ignited. The wood-sulfur experiment is mentioned as a laboratory experiment in the eleventh-grade experimental science book. The aim of this article is to find other carbon substitutes (such as laboratory carbon and organic materials like wood waste from carpentry and paper waste) for wood-sulfur and compare their performance. The results showed that the paper method (immersing paper in Fe2O3/Na2CO3) is preferred over the wood-sulfur method because the entire process is carried out by a single piece of paper, and depending on the paper dimensions, different amounts of the mixture can be used. In methods using carbon and wood waste (wood powder), the components of the mixture are combined together and form a paste-like consistency, which is then ignited. It is worth mentioning that the product obtained from the carbon method is purer qualitatively compared to other methods and contains less carbon because in the other three methods, a larger portion of carbon burns without participating in the reaction. Furthermore, in the carbon and wood waste method, a desired amount of paste can be made and used in several experiments, eliminating the need to repeat the manufacturing process for each experiment. Qualitative observations indicated that the iron production efficiency of these methods follows the order: wood-sulfur < paper waste < wood waste < laboratory carbon.

The purpose of the present was to determine the effectiveness of flipped learning on self-efficacy and academic performance of sixth grade female students in experimental science. The study was quasi-experimental in method with a pre-test and post-test design, and the population of the study included all female grade 6 students of Tabriz, during the academic year of 2022-2023. Cluster sampling was used to select 49 students who were categorized randomly into two experimental and control groups. To collect the data for the study, Jing and Morgan’s (1999) questionnaire and teacher-made tests were initially administered to the experimental and control groups as the pretest. Later, the experimental group passed 10 treatment sessions of 45 minutes in the form of flipped learning while the control group received conventional teaching of science. Following, the treatment, the pos-tests were administered to both groups. The obtained data was later analyzed using descriptive and inferential (Covariance) statistics. The results indicated that flipped instruction has a significantly positive effect on self-efficacy and academic performance of the students.

Essential oil of a species of mountain thymus, extracted by three methods. In the first method through distillation, the extracted essential oil and its compounds were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 75.24%, alpha-terpinol 45.11%, limonene 13.9%, and trans-beta-ocimene 52.7%. In the second method, the essential oil was extracted without solvent using a microwave device, and the main compounds of the plant were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 32.30%, alpha-terpinol 12.14%, limonene 38.11%, and nerolidol 85.9%. In the third method, a combination of ultrasound and water distillation was used for extracting the essential oil, and the main compounds of the plant were analyzed and identified using gas chromatography-mass spectrometry (GC/MS), showing that the main compounds of the plant are linalool 45.23%, 1,8-cineole 98.13%, alpha-terpinol 49.12%, and trans-beta-ocimene 26.6%. In all three methods, the highest percentage corresponds to oxygenated monoterpenes, which are 42% in distillation, 59.87% in microwave, and 50.38% in ultrasound treatment. Then, based on the extraction of the essential oil in each method and their abundance percentage, the antioxidant property of the obtained essences was evaluated using the DPPH free radical scavenging test. The method was chosen based on its non-toxic solvent and its inhibitory time, and the best inhibitory percentage belongs to the microwave extraction method with 5.54% and the distillation method with 40% at a concentration of 5ppm.

The use of visual effects and visual media in chemistry education is very effective and can make the classroom attractive and impress the audience in addition to facilitating the learning of the chemistry concepts and rules. Therefore, this type of learning can be considered a type of visual learning style. In this article, first, a number of the polar and non-polar molecules in high school chemistry books were drawn using GaussView software. Then, in order to achieve the optimized structure of the molecules and their various characteristics, Gaussian software was used. These calculations include optimizing the energy level of the molecule, determining the electric charge of the atoms that make up the molecule, determining the dipole moment of the molecule, displaying the contours around the molecule, displaying electrostatic potential maps, and obtaining the HOMO and LUMO molecular orbitals. From among the different molecules, the structure of water molecule was discussed in more detail. In addition, Gaussian's calculations were performed on some other molecules such as ammonia, methanol, formaldehyde, methane, carbon dioxide, and oxygen. Various molecules were used for drawing to cover many concepts of chemistry. Moreover, the steps of drawing molecules and displaying their properties has also been described.