Carbon monoxide gas detector as integrated chemistry learning media on STEM Science, Technology, Engineering, and Mathematics
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helps the development of collaboration skills and intrinsic motivation Stoica, 2012. The learning is triggered by striving to tackle a problem which may be presented in many forms
such as a description of a design scenario, a curious outcome or an extreme event. Basically, students form teams, organize the work, research and negotiate a response to the problem
Alejandro, 2010. PBL can be used to improve the student achievement related to science and the permanence of information Benli, 2012.
The Indonesia s 2013 National Curriculum was the curriculum that was focused on the output of the educational process in the form of productive, creative, innovative, affective
human through the strengthening of attitudes, skills, and knowledge in multidiscipline Depdikbud, 2013. One of learning approach which can integrated to another concept is
STEM the science, technology, engineering and mathematics. STEM is a learning approach that is integrated with a wide range of disciplines. STEM allows students to learn concepts by
applying four disciplines science, technology, engineering and mathematics in an integrated way Lantz, 2009. STEM eliminate the boundaries between the four disciplines by integrating
these sciences in a single unit a thorough study. STEM education offers students one of the best opportunities to make sense of the world holistically, rather than in bits and pieces.
STEM education removes the traditional barriers erected between the four disciplines, by integrating them into one cohesive teaching and learning paradigm. STEM is an
interdisciplinary approach to learning where rigorous academic concepts are coupled with real-world lessons as students apply science, technology, engineering, and mathematics. The
goal of STEM is the student can be problem solvers, innovators, inventors, self reliant, logical thinkers, and technologically literate Morrison, 2006.
In relation STEM learning approach with PBL learning model, it is required a media that can incorporate the concept of science, technology, and math skills into the learning process.
Media that could be conducted is carbon monoxide gas detector. The process of sample burning and process which are occurred in sensor involved redox reaction. So, carbon
monoxide gas detector can be applied to redox matter.
2. Materials and methods
2.1 Materials
Carbon monoxide CO gas detector was composed of SnO
2
semiconductor based sensor namely MQ-7. Microcontroller ATmega 328 was used for convert analog data to
digital data. Ultra high purity nitrogen was purchased from PT Samator and it was used without further purification for sensor calibration. CO gas was produced by heating of sulfuric
acid and acetic acid.
2.2 Methods CO gas was produced by heating of sulfuric acid and acetic acid according to thermal
method Mattson, 2006. Amount of CO gas was injected to N
2
gas stream which was controlled using flow meter to obtain a certain concentration of CO gas. 2.5, 5, 7.5, and
10 of CO gas was applied for calibration of the sensor. The carbon monoxide sensor and the worksheet were validated by Delphi technique, which was conducted by validators who were
selected from the experts in education i.e. chemistry teachers. The purpose of validation is to evaluate the learning media. The instruments used in this research were Likert scale
questionnaire. Likert scale is used to assess opinion and perception of validator Sugiyono, 2014. Determination of average value of validation test is formulated as follows:
N. Ariesta, R.S. Putra, F. Kurniawan
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= ,
where is average value of validation test, is sum of answer value, and is number of
validator.
3. Results and discussion
3.1 Result 3.1.1 Carbon monoxide gas detector
Carbon monoxide gas detector which is produced is divided into 3 parts, they are: gas sensor and chamber, data processing and data visualization. Chamber is made of glass
because an experiment used was combustion reaction. Data visualization was shown by Arduino application. The gas detector is equipped by air pump to make chamber vacuum.
Carbon monoxide gas detector were shown at Figure 1.
Figure 1. Carbon monoxide gas detector.
2.5, 5, 7.5, and 10 of CO gas was applied for calibration of the sensor. The results obtained for 2.5, 5, 7.5, and 10 of CO gas were shown at Figure 2.
Figure 2. Calibration graph of carbon monoxide gas detector.
Carbon monoxide gas detector has been assessed by chemistry teachers. The data were shown in Table 1.
Carbon monoxide gas detector as integrated chemistry learning media on STEM Science, Technology, Engineering, and Mathematics
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Table 1. The result assessment of carbon monoxide gas detector. No
Aspects
1 Design
3.15 2
Ease of Use 3.11
3 Use
3.19 4
Content of matter 3.24
3.1.2 Student worksheet
Student worksheets were arranged for senior high school students at the second semester in redox reaction material. Worksheet was initiated by introduction about the
application or some examples of redox reaction in daily life. To get concepts about redox reaction, students need to do some activity by using carbon monoxide gas detector. Students
were asked to do experiment, to discuss about the result and then student will get concept by themselves. Based on the concepts which they have gotten, they have been asked to
discuss about some cases about redox reaction. Some exercises also were given in this worksheet. Students could evaluate themselves by using self assessment in worksheet.
Student worksheet has been assessed by chemistry teachers. The data were shown in Table 2.
Table 2. The result assessment of student worksheet. No
Aspects
1 Content
3.18 2
Presentation 3.25
3 Language
3.23
3.1.3 Assessment based on STEM approach and PBL model
Besides experts assessed carbon monoxide gas detector and students worksheet based on some aspects about media and material, they also assessed based on aspects of
STEM Approach and PBL Model. Some aspects of STEM Approach and PBL Model such as: real context, integrated with another discipline, based on student performance, make
student as problem solver and innovator. The data were shown in Table 3.
Table 3. The result assessment based on STEM approach and PBL model. No
Aspects
1 Use of contextual
3.33 2
Encourage the curiosity of student 3.00
3 Integrate another concept in another discipline
4.00 4
Encourage student centered learning 3.33
5 Insert technology
4.00 6
Encourage to self learning 4.00
7 Encourage to be innovator
3.00 8
Encourage to be problem solver 3.00
9 Summative and formative assessment
3.33 10
Encourage to be inventor 3.33
3.2 Discussion
Carbon monoxide gas detector could integrate redox reaction to another concept, they were Dynamic Electricity physic and mathematic. The concept about redox reaction can be
N. Ariesta, R.S. Putra, F. Kurniawan
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generated through the reaction of carbon monoxide gas detector. Student got the concepts about redox reaction through the reactions which were occurred in carbon monoxide gas
detector. Block diagram about the problem description which is conducted was shown in Figure 3.
Figure 3. Block diagram of the problem description.
Figure 3 shows that the concentration of CO gas is directly proportional to the output potential. The resistance of tin dioxide change according to the gas concentration applied.
CO is a reducing gas. When tin oxide is heated, oxygen is adsorbed on the crystal surface with a negative charge. When sensor is exposed in CO gas, the particles of CO gas will be adsorbed
on SnO
2
crystal surface, then reacts with adsorbed oxygen ion O
-
. Then the electrons from the crystal surface are transferred to the adsorbed oxygen. Thererfore the resistance of tin
oxide will change which affect to the output potential.
2 1
2 2
2 x
x
SnO ad
O SnO
O
1
2 2
2 x
x
SnO CO
SnO ad
O CO
2 The reaction of carbon monoxide gas detector was used as example to get concepts about
redox reaction. Reactions 1 and 2 were simplified, so that it could be understood by students easily.
Black pimple, brown color of apple slices and carbon monoxide gas from
combustion of alcohol were used as examples of redox reaction based on
gain and loss of oxygen Students were asked to conclude about
redox reaction based on gain and loss the oxygen
Doing experiment and group discussion with carbon monoxide gas detector to
looked at the electron phenomena in redox reaction. It is used to generate
about the concept of redox reaction based on gain and loss of electron
Students were asked to conclude about redox reaction based on gain and loss of
electron
The total reaction of carbon monoxide gas detector procedure is used to
generate about the concept of redox reaction based on increase and decrease
of oxidation number Students were asked to conclude about
redox reaction based on increase and decrease of oxidation number
Rocket fuel is used to generate about the concept of oxidizing and reducing agent.
Stock Nomenclature of compound
Carbon monoxide gas detector as integrated chemistry learning media on STEM Science, Technology, Engineering, and Mathematics
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In this research, we divide rating s value to be five ranges. Then the result of the rating is interpreted as a criterion. The criteria for media validation are such as very valid, valid, fair,
less valid and not valid. Meanwhile, the criteria for student s response consists of very interesting, interesting, average, less interesting and not Interesting as seen in Table 4.
Table 4. Criteria for media validation. Value
Criteria
3.26 4.00 Very valid
2.51 3.25 Valid
1.76 2.50 Less valid
1.00 1.75 Not valid
The aspects which are assessed in carbon monoxide gas detector are the design, ease of use, usage and the matter which is contained in media. Table 1 shows the instrument of
media validation for carbon monoxide gas detector that from 4 aspects, such as design, ease of use, use and content of matter are valid.
The aspects which are assessed in worksheet are content, preservation and language. Table 2 shows the instrument of media validation for carbon monoxide gas detector that has
the value result at 3.18, 3.25, and 3.23. These values indicate the criteria of the instrument are valid as shown in Table 4.
The aspects which are assessed in carbon monoxide gas detector and worksheet based on STEM Approach and PBL Model such as: real context, integrated with another discipline,
based on student performance, make student as problem solver and innovator. Table 3 shows the instrument of media validation for carbon monoxide gas detector that has the
value result at 3.33, 3.00, 4.00, 3.33, 4.00, 4.00, 3.00, 3.00, 3.33, and 3.33. These values are indicating that the criteria in the instrument are valid as shown in Table 4.
4. Conclusion and remarks
