108 JPAIR Multidisciplinary Research ABSTRACT Critical thinking is one of the 21st Century skills involved in education and is required of students nowadays. The study investigated the critical thinking skills of Junior high school students from three selected public schools in Region 3, Luzon, Philippines. Infusion of the critical thinking in Chemistry through selected teaching strategies of inquiry-based, problem solving, collaborative, and lecture methods. CEU-Lopez Critical Thinking Skills Test (2012) with a reliability test value of 0.87 was used to measure the students’ critical thinking skill levels. Triangulation of inquiry-based teaching, problem solving, and collaborative teaching methods was used as an intervention to determine the enhancement of the respondents’ critical thinking skills and academic performance. Gathered data were processed statistically through descriptive and inferential tests. Results revealed that there is a significant difference in the critical thinking skill levels of Junior high school students in Chemistry. The critical thinking skill levels of the student respondents were highly comparable with respect on their academic performance in Chemistry. The students demonstrated good knowledge, attitude and performance in Chemistry after the infusion of the critical thinking approach in the intervention. The different teaching strategies utilized in the research were Infusion of the Critical Thinking in Chemistry through Selected Teaching Strategies ELEANOR C. REYES http://orcid.org 0000-0002-1457-0341 mecreyes@ceu.edu.ph Centro Escolar University Graduate School Manila, Philippines Vol. 29 · July 2017 Print ISSN 2012-3981 • Online ISSN 2244-0445 DOI: https://doi.org/10.7719/jpair.v29i1.517 Journal Impact: H Index = 3 from Publish or Perish JPAIR Multidisciplinary Research is produced by PAIR, an ISO 9001:2008 QMS certified by AJA Registrars, Inc. 109 International Peer Reviewed Journal applicable in the enhancement of the critical thinking skills of the Junior high school students in Chemistry. Keywords — Pedagogy, triangulation, critical thinking, infusion, inquiry- based teaching, problem solving, collaborative method, Philippines INTRODUCTION Gaps in the learning abilities of the Junior high school students in Chemistry should be determined through experential learning. In any classroom activities, critical thinking should be taught to the students. Alwehaibi (2011), defined critical thinking as a philosophical and practical logical perception, knowledge, precision, and decision to value an idea or theory. Critical thinking skills could be developed and enhanced by the infusion of critical thinking through different teaching strategies. The study involved the exploitation of the inquiry-based, problem solving, collaborative, and lecture teaching strategies in the infusion of the critical thinking. The researcher chose the study to determine the implications of the infusion of the critical thinking into the concepts of Chemistry. In science education, students are taught to think critically, to know the different skills, and learn how to adapt and survive in the academic environment. Alwehaibi (2011) recognized that critical thinking is an essential competency that plays a significant role in shaping the way students learn and think in the new information age. According to Fleming (2010), to become a critical thinker, one must develop a few skills: recognize assumptions, process information honestly, recognize a generalization, evaluate old information and ideas, produce new ideas, analyze a problem, use precise vocabulary, manage emotions, and judge sources. The research involved the enhancement of the critical thinking skills and academic performance of the Junior high school students in Chemistry though inquiry-based, problem solving, collaborative, and lecture method. The study assumed first that there is a significant difference in the critical thinking skill levels of the Junior high school students in Chemistry. Second, that there is a significant difference on the effect of the infusion of the critical thinking using the inquiry-based, problem solving, collaborative, and lecture teaching methods as teaching strategies utilized in the concepts of Chemistry. Triangulation method of the inquiry-based, problem solving, and collaborative teaching strategies was used to infuse the critical thinking into the 110 JPAIR Multidisciplinary Research concepts of Chemistry. Questionnaires on the Inquiry-based, Problem solving, Collaborative, and Lecture Instructional Models were validated by three (3) critical thinking experts, five (5) science educators, and ten (10) high school students who are not involved in the research. This validation of the instrument determined the content validity of the instructional materials used in the study. Instructional materials were used in the teaching strategies to determine the effects of the infusion of the critical thinking into the concepts of Chemistry. Group Respondents Teaching Method X, O1- A,B,C (X1, X2, X3) Type of school where the Instructional Material Model 1, 2, and three were used as the teaching strategies. Y, 01-A, B, C (X4) Type of school where the Lecture Method Model 4 was used as the teaching strategy. Figure 1. Population Sampling Diagram Non- purposive population sampling was used in the population sampling were: f % Class 1- Inquiry-based Method X,01 AX1, X,01 BX1, X,01 CX1 69 17.51 Class 2- Problem-solving Method X,01 AX2, X,01 BX2, X,01 CX2 99 25.13 Class 3- Collaborative Method X,01 AX3, X,01 BX3, X,01 CX3 115 29.19 Class 4- Lecture Method Y,01 AX4, Y,01 BX4, Y,01 CX4 111 28.17 Total 394 100.00 POPULATION SAMPLING (Non-Purposive Sampling) Four Homogenous groups Junior High School Students in Chemistry from Public Schools in Region 3 (Bulacan, Pampanga, and Zambales) 111 International Peer Reviewed Journal There are almost equal in the percentage value of the abovementioned classes (1-4) of the respondents. The data signify that the participants are comparable when grouped according to classes. In the Classes of 1-4, inquiry-based, problem solving, collaborative, and lecture methods were used in the intervention. Triangulation of the aforementioned teaching strategies was applied in the infusion of the critical thinking into the concepts of Chemistry. OBJECTIVE OF THE STUDY The study aimed to determine the effects of the infusion of critical thinking in Chemistry through inquiry-based, problem solving, collaborative, and lecture teaching methods. Critical thinking skills and academic performance of the Junior high school students in the selected schools of Region 3, Philippines were evaluated. The implication of the infusion of the critical thinking to science education is established by knowing the learning gaps of the Junior high school students in Chemistry. METHODOLOGY The study is a quasi-experimental design which focused on the infusion of critical thinking into the concepts of Chemistry by using inquiry-based teaching, problem solving, collaborative, and lecture method as the teaching approaches. Three hundred ninety-four (394) student respondents from the selected public high school of Bulacan, Pampanga, and Zambales were used to determine the effects of the infusion of the critical thinking using the aforementioned teaching strategies. Validated instrument for the respondents’ perception on the criteria of meeting the standard of a good teaching strategy is administered. The critical thinking skills levels of the students were investigated using the CEU-Lopez Critical Thinking Skills Test (2012) in which the “Pre-Test” was determined. The students were exposed using the inquiry-based, problem solving, collaborative, and lecture teaching method in which the critical thinking is infused into the concepts of Chemistry. Thus, after the intervention, “Post Test” was administered to determine the effects of the infusion of the critical thinking into the concepts of Chemistry. The validated questionnaires with a reliabilty test-Chronbach alpha value of 0.78 were used to evaluate the content validity of the instructional models of inquiry-based, problem solving, collaborative, and lecture teaching methods. Concept 1 (Boyle’s Law) and concept 2 (Colligative 112 JPAIR Multidisciplinary Research Properties of Water Solutions) in Chemistry were used in the process of the intervention. The criteria of a good teaching strategy and content validity of the instructional models employed in this study were evaluated. This undertaking consists of Informed Consent and Clearance from the Ethics review Board of the CEU Institutional Ethics and Review Committee (IERC) as approved by the Committee dated September 7, 2015. RESULTS AND DISCUSSION Junior High School Respondents’ Profile According to Age The results showed that the most number of the student respondents are between the ages of 17 and 18 with a percentage value of 41.37 % and 49.49 %, respectively. The highest frequency of the respondents is from the age of 18 while the second highest is at the age of 17. Junior high school students of the selected schools in Region 3 were at the ages of 17 and 18, but there are some at ages 16, 19, 20 and 20 above. This implies that most number of the Junior high school students in selected areas of Bulacan, Pampanga, and Zambales is between the ages of 17 and 18. At the age of 19, there are 24 respondents with a 6.09 % value. The ages 16, 20, and 20 above are with the least number of frequency and with a % value of 1.78, 0.76, and 0.51 respectively. There is no significant difference before and after the infusion of the critical thinking of Junior high school students in Chemistry when grouped according to age. Junior High School Respondents’ Profile According to Gender The results revealed that there are more female than male of the respondents in this study. Two hundred forty-three (243) or 61.68% are female as compared with one hundred fifty-one (151), or 38.32 % are male. This implies that female is almost two-thirds of the total respondents. It was found out that the Junior high school students used as participants of this study are comparable when grouped according to gender. Tamayo, Tayao, Lopez and Mangalile (2014) concluded in their study that there is no significant difference in the sexual category of the freshmen, sophomore, junior, and senior students of CMT CEU Malolos. The profile of the Junior high school students when grouped according to classes is needed to determine the number of the participants in each class where the exploitation of the different teaching strategy is used. For Class 1, 2, 3, and 4 pseudosononyms is used to identify the different teaching strategies of inquiry- based, problem-solving, collaborative, and lecture method. 113 International Peer Reviewed Journal Table 1. Junior High School Participants’ Critical Thinking Skill Levels Utilizing (Inquiry-based Teaching, Problem-solving Method, Collaborative, and Lecture Method) Type of Classes Score Level of Critical Thinking       Interpretation % % Value Value X,01-Class 1 (Pre-Test)   (Post-Test)   AX1, BX1, CX1 0 0 0 0 Master Thinker 3 3 4 5 Advanced Thinker Inquiry-based Method  0 0 0 0 Practicing Thinker 20 23 21 24 Beginning Thinker 40 46 46 53 Challenged Thinker 24 28 16 18 Unreflective Thinker  TOTAL 87 100 87 100   X,01-Class 2 AX2, BX2, CX2 1 1 1 1 Master Thinker 32 32 34 34 Advanced Thinker Problem solving 0 0 1 1 Practicing Thinker Method 33 33 31 31 Beginning Thinker 32 32 21 21 Challenged Thinker 2 2 10 10 Unreflective Thinker  TOTAL 100 100 100 100 X,01-Class 3 AX3, BX3, CX3  0 0 0 0 Master Thinker 29 2 38 26 Advanced Thinker Collaborative 0 0 0 0 Practicing Thinker Method  50 34 45 31 Beginning Thinker 33 23 29 2 Challenged Thinker 33 23 33 23 Unreflective Thinker  TOTAL 145 82 145 82   AX4, BX4, CX4  21 19 16 14 Master Thinker 36 32 36 32 Advanced Thinker Lecture Method  28 25 34 31 Practicing Thinker 13 12 0 0 Beginning Thinker 13 12 10 9 Challenged Thinker 0 0 15 14 Unreflective Thinker TOTAL 111 100 111 100   114 JPAIR Multidisciplinary Research The results reveal that there is an increase in the number of the advanced thinker and challenged thinker after the infusion was done by using the inquiry- based teaching method. However, the data from Table 6 for X,01 AX1; X,01 AX2; and X,01 AX3 with a t-test value of 2, -1, and -1 respectively. This implies that there is no significant difference in the level of the critical thinking skills of the respondents after the infusion using the inquiry-based teaching method. Jones (2013) confirmed that by stimulating a student’s reasoning abilities through the inquiry-based learning, where the students were motivated by the teachers to discover, define a specific concept, acquire knowledge, and make significant observations based on the interpretation of the relevant data and information. However, Cottrell (2011) asserted “giving difficult messages in a way other people could accept an important aspect of critical evaluation. In problem solving method as shown in Table 1, there is an increase in the number of the advanced thinkers and master thinkers. However, results in Table 4 imply that there is no significant difference in the level of the critical thinking skills of the Junior high school students since the t-test value is 1, 1.7, and 0.9 for X,01 BX1; X,01 BX2; and X,01 BX3 respectively using the aforementioned teaching method. Through this, critical thinking encompasses a set of skills including the ability to analyze problems, set information that probes into relevant evidence and figures out fallacious arguments in educational settings as confirms by Birjandi and Bagherkazemi (2012). The results imply that problem solving method was a good teaching strategy to be used in the infusion of the critical thinking in Chemistry. Paul and Elder (2010) cited that a well cultivated critical thinker, raises vital questions and problems, gathers and assesses relevant information, uses abstract ideas, and draws conclusions from a valid data. The assumptions, implications, and practical assesments are needed to find solutions to complex problems. The result exposed that there is an increase in the number of the advanced thinkers in the infusion of the critical thinking where the collaborative method was exploited. Data from Table 3 shows that t-test value of 2.1, -3 and 2.4 for X,01 AX3; X,01 BX3; and X,01 CX3 respectively. This means that there is a significant difference in the level of the critical thinking skills of the respondents using the collaborative method. The result confirms to the study of L. Snyder and M. Snyder, (2008) that collaborative learning and activities could also develop the student critical thinking skills. The intellectual challenge of the students with the assessment techniques could enhance the critical thinking skills of the students. This implies that collaborative method is one of the different good teaching 115 International Peer Reviewed Journal strategies that could be utilized in the infusion of the critical thinking. The findings confirm from the study of Sabiru, Dahir Yusuf (2014) that the students where the collaborative teaching method was exploited significantly enhanced the critical thinking skills and the anxiety was found to be low as compared with the lecture method. Based on the findings, the recommendations were given that teachers should always use collaborative teaching method in Chemistry concepts The result shows that there is an increase in the number of the practicing thinker after the intervention and the infusion of the critical thinking in which the lecture method was used. However, the results show that the t-test value for Y,01 AX4; Y,01 BX4; and Y,01 CX4 is 1, 0, and 0.7 respectively. This means that there is no significant difference in the critical thinking skill levels of Junior high school students using the lecture teaching method. The results implied that lecture method is not the appropriate teaching method to be used in the infusion of the critical thinking in Chemistry. Snodgrass, (2011) on the other hand, revealed that it is important to have a curriculum with new classroom activities involving the infusion of the critical thinking into the concepts of Chemistry. Table 2. Comparison Between the Critical Thinking Skill Levels of the Junior High School Participants and the Teaching Strategy Teaching Strategy (Collaborative) X/SD Pre-Test Post Test t-test V.I. X,01 AX3 X 17 20 2.1 Sig.- Ho (Rejected) SD 7 6.9 X,01 BX3 X 26 24 -3 Sig.-Ho (Rejected) SD 4.7 4.2 X,01 CX3 X 24 27 2.4 Sig. Ho (Rejected) SD 3.9 5.6 @ 0.05 Level of Significance Critical value = 2.021 The finding implies that inquiry-based, problem-solving and the lecture method have no effect on the enhancement of the critical thinking skills after the infusion and intervention were done. Moreover, in the classes of X,01 AX3; X,01 BX3; and X,01 CX3 exemplified that in the t-test value of 2.1, -3, and 2.4 respectively, there were significant differences between the critical thinking skill levels in the collaborative teaching method. The collaborative teaching strategy exploited in the research study was applicable in the infusion of the critical thinking skills of the Junior high school students in Chemistry. It could 116 JPAIR Multidisciplinary Research be effective teaching strategy to be employed to enhance the critical thinking skills of the Junior high school students into the concepts of Chemistry. From the study of Sabiru (2014), it confirms that there is a significant difference found when chemistry students were exposed to collaborative teaching method as compared with performance of chemistry students taught with lecture method of instruction. Those students taught using collaborative learning tend to achieve significantly higher as compared with those taught using lecture method. Table 3. Comparison between the Teaching Strategies and Academic Performance of the Junior High School Participants Teaching Strategies Mean Value SD t-test Value V.I. (Pre-test) (Post Test) (Pre-test) (Post Test) Inquiry- based (X,01-X1) X,01 AX1 88.5 90.8 2.638 3.300 -3.302 S 1st Group 0.685 2.263 X,01 BX1 91.1 92.2 1.324 1.704 2.726 S 2nd Group 0.423 1.154 X,01 CX1 80.9 86.05 4.090 3.457 6.212 VS 3rd Group 0.836 5.195 Problem Solving (X,01-X2) X,01 AX2 77.5 78.4 3.553 3.858 0.795 NS 1st Group 1.094 0.870 X,01 BX2 87.5 89.8 2.451 2.386 -3.970 S 0.596 2nd Group 2.363 X,01 CX2 80.8 85.2 2.056 2.710 8.264 VS 3rd Group 0.531 4.390 Collaborative (X,01-X3) X,01 AX3 77.0 78.4 2.987 3.477 1.584 NS 117 International Peer Reviewed Journal 1st Group 0.899 1.423 X,01 BX3 92.9 94.1 1.766 2.181 2.704 S 2nd Group 0.444 -1.2 X,01 CX3 87.5 89.8 2.451 2.386 -4.145 S 3rd Group 0.570 2.363 Lecture Method (X,01-X4) Y,01 AX4 76.7 78 2.453 3.055 1.524 NS 1st Group 0.835 1.273 Y,01 BX4 82.8 82.9 2.784 4.064 0.263 NS 2nd Group 0.799 0.210 Y,01 CX4 80.0 83.2 4.164 4.463 2.994 S 3rd Group 1.062 3.181 TOTAL @ 0.05 level of Significance Critical Value = 2.021* Legend: 1st Group – First Public School (Bulacan) 2nd Group- Second Public School (Pampanga) 3rd Group- Third Public School (Zambales) The results reveal that there is a very significant difference in the academic performance of the 3rd group of the participants employing the inquiry-based and problem-solving teaching methods. However, there is a significant difference in the academic performance utilizing the inquiry-based teaching method for the 1st and 2nd groups; problem-solving method for the 2nd group; collaborative method for the 2nd and 3rd groups; and lecture method for the 3rd group. There is no significant difference in the academic performance using the problem solving and collaborative method for the 1st group; and lecture method for the 1st and 2nd groups @ 0.05 level of significance. Findings show that the infusion of the critical thinking into the concepts of Chemistry could enhance the critical thinking skill levels and increase the 118 JPAIR Multidisciplinary Research academic performance of the Junior high school students. Moreover, according to Snyder et al. (2008), rote memorization and lecture method could not be used in teaching the critical thinking to the students. Other strategies in teaching such as focusing instruction and assessment techniques could be used to teach the student learners to think critically. The study of Adalikwu, and Lorkpilgh (2013) revealed that students taught with instructional materials performed significantly high in their academic performance as compared with those educated without the instructional materials. The use of the instructional materials improved the students’ understanding of the concepts resulting to a high academic performance. The use of the instructional materials is highly recommended for the teachers to be used in teaching-learning Chemistry. Table 4. Junior High School Participants’ Perception of the Extent of Meeting the Criteria of a Good Teaching Strategy for Concept 1 and Concept 2 Mean Std. Deviation t-value V.I. Inquiry-based Method (X,01-X1) Concept 1 3.318 .348 -7.115 VS Concept 2 3.384 .314 Problem Solving Method Concept 1 3.399 .314 -3.786 VS (X,01-X2) Concept 2 3.450 .284 Collaborative Method Concept 1 3.374 .298 -2.051 S (X,01-X3) Concept 2 3.408 .293 Lecture Method (X,01-X4) Concept 1 3.291 .375 -2.616 S Concept 2 3.319 .322 Table 4 shows that the t-test value of -7.115 and -3.786 @ 0.01 level of significance for the inquiry-based and problem solving teaching method that there is a very significant difference before and after the infusion of the critical thinking into the concepts of Chemistry. Moreover, the t-test value of -2.051 and -2.616 @ 0.05 level of significance for the collaborative and lecture method imply that there is a significant difference after the intervention. Smith and Szymanski, 119 International Peer Reviewed Journal (2013) confirm that the establishment of professional learning communities allows educators to think critically about the methods they are using to teach, and is a good starting point for ideas about inclusion of critical thinking skills in the classroom. The results imply that the aforementioned teaching strategies used in the infusion of the critical thinking perceived by the student respondents could be the best to exploit in the intervention. Inquiry-based teaching and problem solving methods could be the best teaching strategies to use in the infusion of the critical thinking into the concepts of Chemistry. Table 5. Junior High School Participants’ Perception of the Extent of Meeting the Criteria for the Content Validity of Teaching Strategies for Concept 1 and 2 Aspects of Critical Thinking Pre-test Post test Mean S.D. V.I. Mean S.D. V.I. Analyzing 3.35 .417 StronglyAgree 3.38 .397 Strongly Agree Applying Standards 3.28 .398 StronglyAgree 3.29 .397 Strongly Agree Discriminating 2.94 .582 StronglyAgree 3.01 .522 Agree Information Setting 3.38 .405 StronglyAgree 3.38 .404 Strongly Agree Logical Reasoning 3.29 .426 StronglyAgree 3.32 .414 Strongly Agree Predicting 3.21 .497 Agree 3.24 .467 Agree Transforming Knowledge 3.35 .451 Strongly Agree 3.35 .351 Strongly Agree 3.26 .308 StronglyAgree 3.28 .276 Strongly Agree Table 5 shows that Junior high school students strongly agree with respect on analyzing, applying standards, information setting, logical reasoning, and transforming knowledge and agree on discriminating, and predicting aspects for Concept 1 (Boyle’s Law) and Concept 2 (Colligative Properties of Water Solutions) exploited in the infusion of critical thinking. This signify that the teaching strategies used in the intervention could enhance the critical thinking skills of the students. Inquiry-based teaching, problem solving, collaborative, and lecture method that utilized in the infusion of the critical thinking into the concepts of Chemistry met the criteria of a good standard teaching strategy. Halvorsen, (2005) posited that the most experienced teachers recognize that 120 JPAIR Multidisciplinary Research the more information about the personal interests of the students, the more appropriate and engaging the classes will become. Table 9 shows that Junior high school students strongly agree that the two concepts in Chemistry exploited in the infusion of critical thinking with respect on analyzing, applying standards, discriminating, information. VanTassel-Baska, Bracken, Feng, and Brown (2009), McCollister and Sayler (2010), and Tsai, Chen, H. Chang and W. Chang (2013) confirms that critical thinking could be infused in lessons throughout all disciplines by exploiting in-depth questioning and evaluation of data and information. These types of activities could be done in any educational setting with the alternative styles of assessment. CONCLUSIONS Science educators have adequate teaching abilities and experiences that could help the Junior high school students in some selected public schools in Region 3 to enhance their critical thinking skills in Chemistry. The learning gaps of the Junior high school students should be assessed by the teachers to develop their critical thinking skills and improve their academic performance. The learning through experience of the students is the basis for the infusion of the critical thinking into the concepts of Chemistry. Through this, science educators could determine the effects of the critical thinking and its implications to science education. In this undertaking, it was found out that there is no significant difference between the critical thinking skills and the respondents’ profile: age and gender before and after the interventions were done. The research found out that through collaborative teaching method, critical thinking skills of the student participants were significantly enhanced. Moreover, there is a significant difference between the critical thinking skill levels and the academic performance of the Junior high school students in Chemistry in some public schools in Bulacan, Pampanga, and Zambales of Region 3, Philippines. The study determined the implications of the infusion of the critical thinking in Chemistry through the appropriate teaching strategies. Infusion of the critical thinking is one of the important activities in the teaching-learning components of education. 121 International Peer Reviewed Journal TRANSLATIONAL RESEARCH The critical thinking should be infused into the different classroom activities to enhance the level of the critical thinking skills of the students. Critical thinking skills of the students could be enhanced using other teaching strategies and methodologies. The research could be a basis for a proposed instructional model that could be utilize in the infusion of critical thinking in teaching Chemistry concepts. ACKNOWLEDGEMENT A sincerest gratitude to Dr. Erna V. Yabut and Dr. Marcos V. Lopez, for the CEU-Lopez Critical Thinking Skill Test (2012) Instrument tool. To Dir. Malcolm S. Garma, CESO V, Officer-In -Charge of DepEd.Region 3, for the approval and endorsement of this undertaking to the school heads. To the Principals and teachers of the selected high schools in Bulacan, Pampanga, and Zambales, for the appropriate schedule of the classes during the intervention. To Junior high school students, for participating in the infusion of the critical thinking into the concepts of Chemistry. Finally, to Dr. Zenaida B. Los Banos, Dr. Edna Liza M. Victoria, Dr. Avelina Raqueno, Dr. Elmar Malvar, and Prof. Erlina Mendoza, for sharing their expertise in the completion of this research. LITERATURE CITED Adalikwu, S. A., & Iorkpilgh, I. T. (2013). 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