Development of Catalytic Converter Learning Media to Improve Knowledge of Automotive Vocational School Students

Improving the quality of vocational high school graduates (SMK) is relevant to the needs of the world of work and industry. All teachers need support in preparing learning media that are by the competencies needed by the world of work and industry. This study aims to develop a catalytic converter exhaust emission system so that it can be used optimally to increase students' knowledge. The design study which is used in this research is a Four-D device development model which includes 4 stages of development, namely: the Define Stage, the Design Stage, the Development Stage, and the Disseminate Stage. The research subjects were students of class VII TKR in SMK Muhammadiyah 1 Salam, totalling 30 students. The stages of development are carried out properly to produce learning media an attractive and representative catalytic converter exhaust emission system so that it can significantly increase students' knowledge. There was an increase in students' knowledge using the learning media of the catalytic converter exhaust gas emission system as evidenced by the average pre-test score of 57.50% and the post-test result of 88.28% or an increase of 30.78%.


INTRODUCTION
The Development of science and technology on improving the quality of human resources affects the readiness and competitiveness of a country that is facing the demands of the global era [1][2] [3].Science and technology as well as the quality of human resources (HR) are key factors in determining the success and progress of a nation [4].A nation that has the advantage of quality and quality education and human resources will be able to compete in global competition [5] [6].To achieve the national education goals above, improvements in the quality and quality of education are needed.
Improvement of the quality and quality of education, not only includes educational activities between educators and students, but contains the interaction process of educational components, such as learning tools or media, and learning environment [7] [8].

Component interaction-component
Education can be carried out at levels of education that have been provided by the government.Educational levels do not only aim to provide a place in every stage of preparing for the future of citizens.But more importantly, the level of education becomes a facilitator in solving problems and investing in a nation [9] [10].One level of education that is prepared as an educational investment that is good enough to prepare skilled workers in facing the future is the vocational education level (SMK) [11] [12].
Vocational education aims to produce graduates who can easily enter the job market and are capable of entrepreneurship.[37].Catalytic converter or also called a catalyst is a component that is included in the exhaust gas treatment which has a function to clean engine emissions from nitrogen oxide/NOx gas [37].
The existence of a catalytic converter is very important because it greatly affects the success of a vehicle passing the emission test.
In some countries that have special regulations on emissions, a car owner can be fined because his car is not environmentally friendly.The importance of overcoming the demands of these competencies, catalytic converter learning media needs to be planned, created, and developed so that it can increase the knowledge of TKR Vocational High School students [37][38].

RESEARCH METHOD
The  The media expert instrument consists of aspects related to learning media.The grid for instructional media expert instruments can be seen in Table 1.

Table 1. Media expert grid Indicator Item
Ease of operating props 1.2 Suitability of sketches with props 3.4 The practicality of teaching aids in learning 5.6 Effectiveness of props 7.8 The final quality of props 9.10 (Source: [41]) The material expert instrument contains points about aspects related to learning media materials including aspects of learning, material, and content truth.The grid for learning material expert instruments can be seen in Table 2.

Table 2. Grid for material experts Indicator Item
Giving examples in presenting the material 1.2 Conformity of the material with competency standards

3.4
The suitability of the material with the media presented 5.6 Ease of material for students to reliability tests, difficulty level tests.The grid for the knowledge test instrument can be seen in Table 3.The analysis used is: To find the mean or average value by using the formula: To calculate the value of media experts, material experts, media assessment sheets, and learning outcomes, the following formula is used: To be able to give meaning based on the results of media and material experts, use the conversion level of achievement in Table 4.

RESULTS AND DISCUSSIONS
Researchers developed learning media based on the Four-D device development model.

Defining Stage (Define)
The activity of the definition stage is often called a needs analysis.This stage First, front-end analysis by analysing the syllabus of the combustion system and formulating problems related to the exhaust gas emission system learning media.

Planning Phase (Design)
The planning stage aims to design learning tools with the following stages: (1) Preparation of test standards (criteriontest construction).Reference tests are arranged based on the specification of learning objectives and analysis.The results of the difficulty of the questions can be seen in Table 7.
Make a preliminary plan (Initial design).
In the initial design stage, the researcher makes a design drawing and an initial product (prototype) or product design.This stage is carried out to create a media model that is by the learning objectives.8 and Figure 5.After the trial process with several revisions related to the design, a learning media for the catalytic converter exhaust gas emission system was produced which is ready to be disseminated to the general public.The results of the final media product can be seen in Figure 6.Learning media provides a new perspective for learning.This learning media displays a more open form (cutting) so that each part can be understood how it works and the specifications are more in-depth so that students learn more easily.
design study which is used in this research is a Four-D device development model which includes 4 stages of development, namely: the Define Stage (The planning stage aims to design learning tools), the Design Stage (make design drawings and initial products (prototypes) or product designs), the Development Stage (tool development with expert input), and the Disseminate Stage (socialization of research results).The stages of the research can be seen in Figure 1.Volume 6, Number 2, November 2021 ISSN 2528-2611, e-ISSN 2528-2700

Figure 1 .
Figure 1.Stages four-D device development model [40] The object of the research was carried out at SMK Muhammadiyah 1 Salam.Due to the pandemic period, the research subjects taken were 5 students for the small group (trial 1) and 15 students of class VII for the large group (trial 2).The data collection instrument consisted of a questionnaire and a knowledge test sheet (test).The questionnaire serves to measure the responses of media experts and material experts.While the test serves to measure the results of knowledge after the application of learning media for the catalytic converter exhaust gas emission system in the Basic Automotive Engineering subject of combustion system competence.

understand 7 . 8 Clarity of sound reading material 9. 10 (c
Source: [41]) The knowledge test instrument uses the taxonomy method with question clarification divided into six parts, namely Knowledge, Understanding, Application, Analysis, Synthesis, and Assessment or more popularly called the C1-C6 method through a series of statistical tests such as validity tests, Volume 6, Number 2, November 2021 ISSN 2528-2611, e-ISSN 2528-2700

Figure 4 .
Figure 4. Media revision results After the learning media and material instruments have been revised, the next step is to conduct trials.The trial was conducted twice to measure the achievement of students' knowledge.The first test group was the control class and the experimental class with a total of 30 students.The control class group involved 15 students of class VII A of TKR in SMK Muhammadiyah 1 Salam.While the experimental class trial involved 15 students of class VII B of TKR in SMK Muhammadiyah 1 Salam.The results of the knowledge test of the control class and the experimental class can be seen in Table8and Figure5.

Figure 6 .
Figure 6.Final product of catalytic converter exhaust gas emission system learning mediaStage of Dissemination (Disseminate)In the context of media dissemination, it is carried out by socializing learning media for the catalytic converter exhaust gas emission system in the form of scientific publications in national journals so that it can be used by the general public.

Table 3 .
Knowledge test grid Indicator Item

Table 6 .
Preparation of knowledge test standards results of instrument validation, the indicator is above the standard r table 57, namely > Volume 6, Number 2, November 2021 ISSN 2528-2611, e-ISSN 2528-2700

Table 7 .
Classification of problem difficulty levels

Table 8 .
Comparison of knowledge test results for control class and experiment class