Abstract

Chemistry is the science of experimentation, so developing experimental capability (EC) for students through teaching chemistry is an important and indispensable issue. Depending on the level of the student, the facilities of the school, the teacher may choose different measures to develop the experimental capacity for the student. In this article, we have built a static channel system, animated channel system and apply some solutions using them in the form of problems such as: formation of new knowledge, practice consolidation knowledge, practice the experiments and extracurricular activities in organic chemistry in high school to contribute to the training and development of experimental capabilities for students.

1. Introduction

In the system of competency that needs to be form and developed EC for students, there is one of the specialized capacities for teaching and learning in Chemistry, an experimental scientific subject, most of the theory is based on empirical results. EC is not only important for students in the process of learning but also continues to be formed and developed in life. There are a number of teaching aids that can be used to assist teachers in the development of physical education for students, such as experimental films, laboratory equipment, experiments, pictures, diagrams. In the world there have been a number of researches mentioning this issue such as: Avi Hofstein, Oshrit Navon, Mira Kipnis, Rachel Mamlok-Naaman in Developing Students’ Ability to Ask More and Better Questions Resulting from Inquiry-Type Chemistry Laboratories ¹. Understand the impact of laboratory activities on learners' asking questions ability.

A. L. Chandrasegarana, David F. Treagusta and Mauro Mocerinob studied the development of a two-tier multiple-choice diagnostic instrument for evaluating secondary school students’ ability to describe and explain chemical reactions using multiple levels of representation ². Describe the assessment of the ability to describe and explain the chemical reaction of students.

In Vietnam, there are many researches on capacity development, experimental practice capacity or the use of visual aids in teaching. For example, Ly Huy Hoang has "investigated the real situation of experimental capacity development for students in universities" and "built and used empirical exercises to develop the capacity of experimental practice Chemistry for students at the University" ^{3, 4}; Pham Thi Binh and her coworkers conducted "Building the Chemistry Exercises for Developing Chemical Practicing Capacity for Students in High Schools" ⁵; On other subjects, Tran Thi Thanh Thu proposed "the method of forming experimental capacity for physics pedagogical students ⁶ and other related works ^{7, 8, 9, 10}.

In general, these researches are mainly to build the system of means such as documentary films, chemistry experiments, pictures, drawings, tables, etc., in the direction of creating excitement, development of thinking, practicing capacity to improve the learning outcomes for students. However, only at the level of collecting, synthesis of specific materials, images, sometimes even discrete. Most of them have not studied the method of applying the above means in a specific method or teaching technique. There are very few research topics in the field of natural resource development for students using science. In this article, we are building a channel system which is stored in the form of website, proposing some measures on the use of visual aids including static and dynamic programs such as drawing, picture, graph, tissue The course aims to develop students' EC in teaching high school organic chemistry to students in order to train and develop their skills to promote the spirit of self-learning, to love the subject, to improve the learning outcomes for students, to contribute to the goal of educational innovation.

2. Content

Using a combination of methods of analysis, synthesis and systematization in the study of relevant documents. Investigate the real situation of the use of visual aids, the problem of developing the EC for students and pedagogical experiment to test the practical value of the research results. Use mathematical statistical methods to process data; have the comments, authentic assessments.

System of visual aids: images, charts, videos,... evaluation tests, tables, mathematical formulas.

- High school organic chemistry’s channel system for the development of EC for students.

- Methods of developing EC for students.

2.4.1.1. Concept and classification

- According to the Vietnamese Dictionary: "Images of human or things are expressed in a specific way or by impression in the mind" ¹¹.

- According to the Second Encyclopedia of Vietnam: In philosophy, images are the result of object reflection, the object of human consciousness is sensation, perception, concept, judgment. This is an expression or representation of an object, a person in the visual arts (painting, graphics, sculpture) ¹².

- In this article, we conceptual images are what give us "visual perception" similar to "visual perception" from real phenomena and thus can describe the appearance of things on the way it is.

- Channels include:

Static channels: These two-dimensional images are represented on the plane: paintings, graphs, images of real objects taken... or three dimensions: sculptures, models, 3D images...

+ Animated channel: "Animated images recorded from real objects by electronic or man-made devices" ¹³ thanks to the support of informatics software such as experimental video, simulation solution,...

2.4.1.2. Principles of selection, construction and use of channels for developing EC for students

a) Principles for selection, construction of channel system

- In order to be able to develop self-directed thinking, the content of the visual channel must be directed to the experiment, such as an image or a video describing how the instrument was fitted, the experiments performed, the phenomena and the applications of the experiment. ...; plot of experiment results;

- The process of building a video channel system for the development of EC for students

+ Determine the purpose of using the visual channel: using the visual channel to develop the component capacity of the EC. What knowledge is gained in the content of the unit?

+ Determine how to use the video channel: use the projector, studying card, hanging board for students to observe, students self-design and construction, games,...

+ Conduct selection and construction of the channel in accordance with the purpose and use of the previously determined. Notes: For pictures, drawings, models,...: color harmony not too much cumbersome and reasonable layout. For video experiments or simulation experiments, ...: the image must be clear, must show the focus and transmission of lessons learned.

b) The principle of using the channel system

If teaching aids in general and visual channel in particular is used properly, science will increase the effectiveness of teaching and learning activities. Therefore, when using visual channel, the following principles should be ensured:

- Use the EC in the order of the teaching plan, only when necessary. Advance instruction should be given to students to observe. Clean up after finishing activities to avoid distracting students.

- Ensure all students are observed clearly; To store in a scientific way (can be arranged in sequence, each type,... can set up electronic library);

- Do not use too long or repeated a channel type in a lesson; Flexible and reasonable change to attract students; Use at a moderate level.

- Experimental capacity: EC definition in Vietnamese dictionary ¹¹: "Experimental capacity is the ability to apply the knowledge, skills, attitudes and excitement to act in an appropriate and effective manner. in the varied situations of life. "Based on the above definition, combined with the study of the EC viewpoints of some authors ^{4, 6}, we have assumed that: EC is the ability to apply the knowledge, Plan and implement plans to address a specific problem in learning as well as in life. In this article we focus on EC in chemistry, which is one of the basic concepts of chemical teaching, demonstrating the practical experiments of students in the study of chemistry.

- The structure of EC using visual channel in Chemistry has four components:

+ capacity recognizes experiments from visual channel.

+ capacity Plan the experiment and experiment.

+ capacity Observation, description, explanation of phenomena expressed through visual channel.

+ capacity processes information obtained from experimental results.

- The manifestations of EC through the visual channel include:

+ Identify the tools, chemicals, the content of knowledge related to experiments observed from photos, videos, models, research questions.

+ Proposed experiments, selection of tools, chemicals; Identify factors that affect chemical experiments such as temperature, concentration, chemical size, etc.; equipment, safety, success; Chemical treatment, equipment after the experiment reasonable.

+ Identification of details to be observed; Describes the transformational elements represented in pictures, graphs, and videos; write chemical equation explaining the phenomenon of experiment, natural phenomena observed from pictures, video.

+ The data can be processed from charts, graphs, ... (can perform necessary calculations); compare, analyze, draw conclusions from the information obtained through photos, videos, graphs; Suggest other experimental options.

Method for surveys was described in ¹⁴. We investigated for 140 teachers and 576 students to find out at the National High School and Van Canh ethnic high school in the province of Binh Dinh and Gia Lai including Nguyen Khuyen High School; Quang Trung high school. We note that most teachers and students think that the development of EC in Chemistry is very necessary (57.14% teachers, 43.66% students).

At the present, there are 61.76% of lecturers rated good and 8.8% of teachers highly rated. During the lessons, teachers still use visual channel, but only at the level of 47.06% of teachers sometimes use; 44.12% of teachers use regularly; 8.82% rarely used. Of these, 82.35% of teachers find it difficult to use the visual channel, which is finding, cutting. This problem is mainly concentrated in district schools and limited facilities.

Based on the results of the survey, it was found that the development of biochemistry for students in chemistry teaching is necessary and the use of visual channel is relatively effective in this field

2.4.4.1. Construction process

- Determine the purpose of using visual channel: What is the purpose of using visual channel? What knowledge is gained in the content of the unit?

- Determine how to use the visual channel: use the projector, study card, board for students to observe, self-design and construction, games, ...

- Conduct selection, develop the visual channel in accordance with the purpose and use of the previously determined. Attention: For pictures, drawings, models...: color harmony, not too much cumbersome, reasonable layout; For video experiments, simulation experiments,...: clear images, must show the focus and transmission of lessons learned not rampant.

2.4.4.2. Website design to store visual channel system

Website design helps us to store the visual channel system has built in the process of teaching and learning to help teachers and students to use their teaching easily, simply and dynamically through the google site ^{15, 16}.

Step 1: Create a Gmail account

Step 2: Sign in to Gmail

Step 3: Visit the link https://sites.google.com

Illustration of the visual channel data interface on the website (Figure 1).

The visual channel is built with video clip resources for experiments, practical imagery for experiments, visual exercises, thinking diagrams. According to the logic of hydrocarbons, the hydrocarbon derivatives

Visit link: sites.google.com/site/kenhhinhhoa11.

2.4.5.1. Use the visual channel in the form of a lesson to form new knowledge

When teaching a new form of knowledge to students, teachers do not simply provide knowledge but must design and organize teaching in a positive way for students to discover themselves, gain knowledge in a way. It is also a requirement in the current orientation of teaching and learning. Depending on the content and purpose of the lesson, teachers choose different teaching methods. The use of visual channel in teaching a new subject in the direction of developing the EC for students does not only help students practice and develop their hands-on experiments, but also help them gain an interest in learning and easily acquire new knowledge. thereby improving the learning outcomes.

Example 1: To help students gain knowledge about the incomplete oxidation of oxide in analytical articles. 2. The teacher can use the organization channel as presented in Figure 2.

- Teacher prepares the above picture (can be in study card, projector or board, ...)

- Teachers prepare tools, chemicals and ask: Look at the image of the reaction of CuO with ethyl alcohol in the picture above. Select the tools, chemicals to conduct safety experiments, describe the experiment phenomenon and write the chemical equation explain.

Example 2: In order to form new knowledge: "Acidity of carboxylic acids" for students in teaching their Carboxylic Acid, teachers can organize the observation video of the acidity of Acetic Acid to help students recall. This has been studied in the 9th grade. From this, the structure and generalization are analyzed into the properties of carboxylic acids. Some images from the video are showed in Figure 3.

- Before teaching, teachers give students a video to watch, observe and describe the phenomenon occurring during the experiment, writing the chemical equation of the reaction.

Through visual observation and implementation of teacher requirements, students have developed the ability to identify chemicals and tools; conduct experiments; determine the factors to be observed; Describes phenomena occurring and from there seeks to explain phenomena with learned knowledge.

2.4.5.2. Use the visual channel in the form of exercise, reinforce the knowledge.

Exercising, strengthening will help students remember long, deep understanding new knowledge has just formed. Using video channels through video clips or drawings of chemical tools will help students better absorb, create interest in learning and can develop intellectual property for students relatively effective.

For example, to reinforce the properties of teachers, the following can be used to design the exercise using the channel: In the laboratory, ethane gas is prepared from ethanol as showed in Figure 4.

In the following substances: ethyl alcohol, water, pumice stone, ethylene, thick sulfuric acid, dilute sulfuric acid. A, B, C, D, E are turned:

1. Ethylic alcohol, water, ethanol, dilute sulfuric acid, pumice stone.

2. Ethylene glycol, dilute sulfuric acid, ethylene, water, pumice.

3. Ethylic alcohol, concentrated sulfuric acid, ethylene, water, pumice.

4. water, solid sulfuric acid, ethylene, ethyl ether, pumice.

Students discussing the above content will develop the ability to recognize experiments: select the appropriate tools and chemicals to conduct successful experiments, safety, contact with relevant knowledge learned in alcohol.

2.4.5.3. Use the visual channel in practice form

To develop EC for students, not only in the classroom but also at home. The implementation of some practical experiments will increase the quality of teaching, helping students to practice a variety of skills such as selection of tools, chemicals, observation, description, explanation of the phenomenon, ... And guidance of the teacher in this activity is needed. However, if only verbal instructions, the student is often difficult to imagine because there are too many operations to perform, so using the visual channel to support will bring better results in this case.

For example, teachers give students visual observation of the process of making wine and ask them to do at home to obtain specific products and to indicate some conditions for successful implementation (Figure 5).

Students who do this requirement will develop the capacity to select tools, chemicals, conditions and operations to obtain quality products.

2.4.5.4. Use the visual channel in the extracurricular activities

Extracurricular activities are essential activities in the school. It provides students with an enjoyable experience that is an opportunity to apply their knowledge into practice. Embracing stress in the learning process. In this activity, teachers can use the video channel to design games such as ringing the golden bell, crossword puzzle, chasing word capture, and creating a healthy playground. Some of capacity needed for children, including EC.

Example 1: In the ringing game teachers can design the question as presented in Figure 6.

From Figure 6, the following conclusion is most accurate:

A. The reaction between phenol and bromine needs to be heated up.

B. Benzene reacts with bromine solution under normal conditions.

C. Benzene is easier to carry out bromine substitution than phenol.

D. Phenol is easier to carry out bromine substitution over benzene.

Responding to this question will relate the learned knowledge of benzene and phenol, developing the ability to observe and draw conclusions from the results of experiments.

Example 2: In the chase game, the teacher asks the following questions: What chemical reaction is mentioned in the picture below?

Students answering this question will relate the knowledge they have learned about mirroring, the phenomenon, the application of the reaction, the development of the ability to observe, to recognize the experiment.

Pedagogical experiments will be conducted in the 2017 - 2018 school year, in two high schools in Binh Dinh province, including National high schools and Van Canh high schools for ethnic minority pupils and two high schools in Gia Lai province: Nguyen Khuyen high school and Quang Trung High School with 140 teachers and 576 students. The design of teaching plan using the visual channel to develop the EC for students combined with teaching methods of polarization. Evaluate the results of the experiment through the self-assessment checklist and teacher assessments together with the results of the test of assessment of EC is processed by mathematical statistical method.

Analysis of the checklist we found that the students after the impact of EC better than the effect expressed in the percentage of students achieving good, good in each criterion of the students after impact is always higher than the students active and weak, the average is always lower. Some specific criteria are as follows:

- Determine the equipment, chemicals, contents of knowledge related to experiments being observed

From image, video, model: % students hit a good level in students after impact was 62.16%, 0% students are weak, in students before impact, % students reached a good 14.71% of which 2.94% weak.

Determining the factors influencing the chemical experiment: In the students after impact, the percentage of students was good, 79.73%, while in the previous students the impact was only 42.65% This.

- capacity installed tools, performed safety tests, successes: 35.14% achieved good grades, no students at low level after impact, while in students before impact only 13.2% achieved good and 8.82% students is weak.

Considering the other criteria of EC from the data obtained gives similar results (Table 2).

The mean value of the experiment class was higher than that of the normal class (3.12> 2.55). V value ranges from 10% to 30%, showing reliable results. The S value of the experiment class is smaller than that of the normal class such that the dispersion of the experiment class is lower than that of the normal class. ES (0.76), in the range of 0.5 to 0.79, can confirm that the difference in mean values is 99% (t> t_α).

Based on the results of the analysis, the scientific basis of the measures we use has had a positive impact on the development of EC for students.

3. Conclusion

From the study of the theoretical foundation of the visual channel and EC. We have set up a visual channel system on the website, including experimental videos, pictures, diagrams, drawings, and so forth. Beside that we suggest solutions for developing EC for students by teaching by visual channel through teaching new research papers, exercises, experiments in high school and extracurricular activities. Experimental results were conducted in two delta provinces and Tay Nguyen. The feasibility of using these measures in the development of EC for students. Help teachers to maximize the effect of using the visual channel through chemical exercises and other classroom activities, extracurricular activities to achieve teaching goals, develop maximum potential inherent of each learner, response The current trend of education and the necessary for students to enter life in the future.

References