In the 21st-century educational landscape, the primary challenge is no longer just accessing information, but developing the capacity to discern and evaluate its reliability (Arruti & Paños-castro, 2025). Students in digital environments frequently encounter conflicting narratives, which require robust critical thinking skills to distinguish facts from misinformation (Kops et al., 2025). As a result, the educational paradigm has transitioned from simple content delivery to content discernment, instructing students to analyze, evaluate, and reconstruct meaning (Abdelhalim et al., 2025; Daff et al., 2024).

The demands of the digital age and the realities of the field, however, differ greatly. According to a number of educational research reports published in Indonesia between 2024 and 2025, students' critical thinking abilities are still comparatively low, especially at the junior high school level. The primary cause has been found to be the prevalence of teacher-centered learning, where students are more likely to passively listen, memorize test materials, and see little use of active learning models in the classroom.

Education in Social Studies (IPS) has a special duty in this regard. The primary objective of IPS, a field that studies human life systems in social contexts, is to produce citizens who can successfully address social issues. But this admirable objective is frequently thwarted, and there is a big disconnect between the ideal goals of education and the actual state of affairs. According to research by Dursun & Aykan (2025), many institutions continue to use a teacher-centered approach to teaching and learning. Because of this, students are more likely to be passive and spend more time listening and learning information, which has an impact on their capacity for self-improvement and reasoning (Haji & Atemnkeng, 2024). Although the school has adopted a number of active learning models, "in reality, many students still appear confused and unable to understand how to complete paragraphs," according to a preliminary study done for this research at SMPN 2 Pangenan. Students "lack proficiency in critical thinking when solving problems in Social Studies learning," according to this, demonstrating a glaring discrepancy between curriculum goals and real classroom results.

A pedagogical intervention that converts passive learning into participatory learning is necessary to close this gap. To address this particular problem, this study suggests the Complete Sentence Learning Model (Kalimat Lengkap) as a focused pedagogical intervention. According to Aji (2016), this model is a teaching strategy that places an emphasis on students actively filling in blank sentences or paragraphs based on the context of the subject matter being covered. According to (Usman et al., 2019), the Complete Sentence model is a cooperative learning approach that is "simple and easy to apply." Students learn by using the given key answers to complete imperfect paragraphs. The model is described as a method that takes into account pupils' capacity for text fragment prediction. In actuality, it is a collaborative exercise that promotes students to read critically, discuss, evaluate modules, and create meaning. Presenting the material, forming diverse groups, having discussions to finish worksheets (incomplete paragraphs), and drawing conclusions are all steps in the process. Cognitive skills at levels C3 (applying information) and C4 (analyzing and classifying information) are directly trained by this process (Wildgruber et al., 2025).

Because of its theoretical connection to the growth of critical thinking abilities, this intervention was selected. Ennis (2011) defines critical thinking as rational, introspective thought aimed at making decisions about what to believe and what to do. Its goal is to evaluate a viewpoint or concept using reasonable standards. The Complete Sentence model forces students to move beyond simple memorization to the fundamental critical thinking skills of contextual sentence analysis, active discussion, and answer validity evaluation (Shabrina et al., 2025).

Even though the model has promise, there is still a big gap in research. Prior research on the Complete Sentence model in Indonesia has primarily concentrated on overarching cognitive learning outcomes or fundamental vocabulary acquisition (Usman et al., 2019). For instance, a recent undergraduate thesis demonstrated the model's effectiveness in improving general student learning outcomes in Social Studies, yet it did not explicitly isolate or measure the improvement of higher-order critical thinking skills. There is insufficient empirical evidence directly associating the 'contextual sentence completion' mechanism with the enhancement of analytical (C4) and application (C3) skills in junior secondary Social Studies. This study fills this gap by directly investigating how the pedagogical components of the Complete Sentence model promote critical reflection and logical reasoning amidst intricate social dynamics.

This study employs a quantitative approach using a quasi-experimental method. The research design applied is the Non-Equivalent Control Group Design. This design involves one experimental group that receives the treatment (the Complete Sentence model) and one control group that receives conventional instruction. Both groups are administered a pre-test to measure their initial abilities and a post-test to assess the impact of the treatment (See Table 1).

Legend :

        : Pre-Test for both groups

        : Post-Test for both groups

X         : Treatment (The Complete Sentence model)

C          : Conventional Instruction (Teacher-centered method)

The population of this study consists of all eighth-grade students at SMPN 2 Pangenan, Cirebon Regency, totaling 146 students. The method used for sampling was purposive sampling. Classes VIII A and VIII D were chosen based on the subject teacher's suggestions and a look at their academic records from the previous semester. This showed that both classes had similar baseline cognitive abilities and demographic characteristics. The experimental group, Class VIII A (30 students), received the Complete Sentence learning model, while the control group, Class VIII D (30 students), received traditional instruction.

The research intervention took place over four meetings, each lasting two 40-minute sessions. In the experimental group, the Complete Sentence model strictly guided the learning sequence. The teacher set the learning goals, gave an introduction, and made groups of 2–3 students that were not all the same. After that, the students were given worksheets with incomplete paragraphs and worked together to figure out the context clues and come up with the right endings. This was followed by a verification phase. On the other hand, the control group taught in a very traditional, teacher-centered way. The teacher was in charge of the session because they gave direct lectures, explained things on the whiteboard, and had students take notes on their own. There were no group tasks or structured peer discussions.

This study used two main tools to collect data. The initial instrument was a critical thinking skills assessment comprising twenty items, specifically formulated to assess cognitive processes at levels C3 (Applying) and C4 (Analyzing). Although critical thinking theoretically includes a wider range of advanced cognitive skills (like evaluating and creating), this study intentionally limited its assessment to C3 and C4. There were two main reasons for this choice. The fundamental mechanism of the Complete Sentence model requiring students to use context clues to fill in missing information naturally fits with applying what they already know to new situations (C3) and figuring out how parts of a text are related to each other (C4). Second, for eighth-grade students heavily accustomed to teacher-centered rote memorization (C1 and C2), mastering application and analysis represents the most crucial and realistic foundational leap toward advanced critical thinking. The test items operationalized these skills by presenting students with contextual social scenarios, requiring them to apply IPS concepts to solve novel problems (C3) and systematically break down informational elements to deduce logical answers (C4). Consequently, focusing on C3 and C4 provides a targeted, sufficient, and highly valid parameter to capture the direct pedagogical impact of the intervention on students' critical reasoning.

Before being used, both instruments were tested for validity and reliability. All 20 of the critical thinking test items were deemed valid, according to the validity test results (r-calculated > r-table 0.254). A Cronbach's Alpha value of 0.774, which is classified as "high reliability," was obtained from the test items' reliability test. With a Cronbach's Alpha value of 0.834, which is classified as "very high," all 20 of the model implementation questionnaire's items were likewise deemed valid.

To answer the three research questions, data analysis was done. Descriptive percentage statistics obtained from the questionnaire data were used to analyze the model's implementation (research question 1). Pre-test and post-test data from both groups were examined using inferential statistics in order to test the hypotheses (research questions 2 and 3). Prerequisite tests, such as the Normality Test (using Kolmogorov-Smirnov) and the Homogeneity Test (using Levene's Test), were carried out before the hypothesis was tested. After confirming that the data were normally distributed and homogeneous, hypothesis testing was carried out using the Independent Samples t-test. The purpose of this test was to ascertain whether the experimental group, which employed the Complete Sentence model, and the control group, which received traditional instruction, differed statistically significantly in their post-test mean scores.

3.1. Instrument
This instrument was designed to measure the implementation of the Complete Sentence Learning Model. The application of the model is divided into nine main indicators based on the theoretical steps proposed by Hanafiah and Suhana in 2009, as presented in Table 2.

This study operationalizes critical thinking skills using levels C3 (Applying) and C4 (Analyzing) from Bloom’s Taxonomy framework, as referenced in Taxonomy of Thinking by Sunaryo and Wowo, as presented in Table 3

3.2. The Implementation of the Complete Sentence Learning Model
An in-depth analysis of the questionnaire data (summarized in Table 4) revealed the key components that contributed to the success of this implementation. This success was driven by the teacher’s procedural adherence and, more importantly, by the high level of students’ cognitive engagement. (1) Student Acceptance: There was a very high level of student agreement regarding the impact of the model. A total of 93.3% of students agreed or strongly agreed that the Complete Sentence model “enhanced their critical thinking skills.” (2) Procedural Adherence: According to 93.3% of students who agreed that the teacher "read aloud the competencies to be achieved" prior to the start of the lesson, the teacher successfully carried out the model's essential steps. (3) Active Participation in Core Tasks: Students demonstrated active participation in the model's core tasks. Up to 90.0% of students said they "read until they understood and memorized the worksheet that had been discussed." These results are in line with systematic review of active learning, which emphasized the importance of well-designed interactive models in promoting engagement and improving critical thinking.

As Shown in Table 4, despite falling short of 100%, the 79.33% score actually supports the study's conclusions. The results of the questionnaire point to a crucial detail: not all students find this model to be "easy." Just 66.7% of students said they felt "capable of completing the sentences," as indicated in Table 4. This is proof that the task worked as intended, not a flaw in the model. The result indicates that students experienced the expected level of cognitive effort or cognitive load. Instead of merely reproducing answers, they were required to discuss, analyze, and negotiate ideas in order to complete the paragraphs an authentic demonstration of cognitive skills at levels C3 (Applying) and C4 (Analyzing) targeted in this study.
The following is a summary of the percentage of implementation data for several key indicators from the questionnaire distributed to 30 students in Class VIII A, presented in Table 5.

In summary, the “Good” implementation score (79.33%), supported by these specific data, establishes strong treatment fidelity. This finding allows the argument to be made with confidence that the significant differences observed in test results (discussed in the following section) are a direct consequence of the Complete Sentence learning model treatment, rather than an artifact of chance or poor implementation. Students clearly understood the material after their peers concluded the lesson (Item 13). With a maximum score of 120, this indicator received the highest score of 111, indicating a 92.5% success rate. Peer-to-peer understanding is very effective because it supports the Complete Sentence model's closing process, which concludes with student-led conclusions. Students' critical thinking abilities were enhanced by using the Complete Sentence model (Item 7). This indicator achieved a score of 106 out of 120 (88.3%).

The high percentage serves as direct validation from respondents that the model through its discussion process and paragraph completion activity is strongly believed to significantly enhance their critical thinking abilities. The high score on this indicator demonstrates that the essential component of the model, namely group discussions to complete the unfinished worksheets, was effectively implemented and positively experienced by the students. These implementation findings guarantee strong treatment fidelity, consistent with recent research, including, which underscores that effective execution of structured collaborative models in Social Studies leads to genuine enhancements in student cognitive outcomes, rather than being attributed to chance or inadequate implementation.

3.3. Students’ Critical Thinking Skills Before and After the Treatment
Student performance data are presented in Figure 1, which illustrates the Comparison of Mean Scores of Critical Thinking Skills (N=60) and is visualized in Figure 1.

Figure 1 shows a striking difference between the mean scores of students’ critical thinking skills in the experimental class (VIII A) and the control class (VIII D). These findings are consistent with broader educational research, including studies by Siregar et al. (2024), which indicate that structured collaborative learning methods substantially surpass traditional lecture techniques in enhancing students' critical thinking skills.

While the control class only saw a minor increase from 65.83 to 68.83, or roughly +3.00 points, the experimental class's average score improved by +14.67 points, from 68.50 to 83.17. This discrepancy suggests that, in comparison to traditional lecture-based training, the Complete Sentence learning model had a far greater impact on enhancing critical thinking abilities. The Complete Sentence model can encourage students to memorize and integrate the material they have studied, develop critical analysis and reflection skills during the learning process, and help them complete sentences correctly.

The significant rise in the experimental group's scores cannot be exclusively ascribed to the novelty of a new model; instead, it is fundamentally linked to the distinct cognitive mechanisms of the Complete Sentence intervention. The model forces students to go beyond just receiving information and instead work on reconstructing meaning in context. Students can't just memorize things when they see an incomplete paragraph. Instead, they need to use guided inference, which means using clues from the text around them and applying what they already know (C3) to figure out what makes sense to add. Also, the way the model is set up requires people to work together to think. In their small, diverse groups, students must explain how they think, look at information (C4), argue about possible answers, and defend their logical choices before they can agree on one. This dynamic encourages students to be very responsible during discussions because each group member is in charge of the final text. In the control group, knowledge was passively received without peer-driven argumentation. In the experimental group, on the other hand, critical thinking was turned from an abstract idea into an active, social practice through a dialectical process.

The Independent Samples t-test revealed a statistically significant difference between the two groups, with a value of t-value = 5.749 and a significance level of p = 0.000 < 0.05. The Complete Sentence model is more successful than traditional instruction at helping students develop their critical thinking abilities, as demonstrated by the Mean Difference value of 14.333 points. The idea that learning through cognitive and cooperative activities can be a crucial tactic for improving students' higher-order thinking abilities in 21st-century education is thus supported by these findings. In comparison to traditional approaches, collaborative approach in conjunction with interactive multimedia greatly increased students' critical thinking efficacy. Research by Febrianto & Rohana, (2024) found that this approach not only hones higher-order thinking skills but also fosters students' social and emotional skills to face global competition.

3.4. Significant Differences in Critical Thinking Skills (Hypothesis Testing)
The hypothesis testing was preceded by prerequisite tests, both of which were satisfied: the data were normally distributed (Kolmogorov–Smirnov Sig. = 0.062 > 0.05) and had homogeneous variances (Levene’s Test Sig. = 0.791 > 0.05). The results of the t-test, summarized in Table 6, provide conclusive statistical evidence.

The statistical significance value (Sig. = 0.000) provides very strong evidence to reject the possibility of chance. This indicates that the probability of obtaining a mean difference of 14.333 points by coincidence is almost zero (less than 0.1%). Based on this finding, the Alternative Hypothesis (Ha) that there is a significant difference in students’ critical thinking skills is officially accepted. This result confirms that the Complete Sentence learning model is significantly more effective than conventional learning methods. Additionally, the high t-value (5.749) indicates that there is a significant and substantial difference between the two groups. This result supports the claim that the pedagogical intervention has a significant and noticeable effect. Permana et al. (2022) found that students' physics learning outcomes were significantly improved when the Complete Sentence method was combined with Giving Questions and Getting Answers in secondary schools. The t-test results demonstrated a significant difference between before and after the method was implemented, confirming the method's efficacy in improving student learning outcomes.

The education sector desperately needs interventions that have been shown to be successful in the face of the pervasive disinformation crisis. Such a contribution is made by this study. A low-tech model like the Complete Sentence approach can be an effective and statistically significant tool for developing cognitive skills at levels C3 (Applying) and C4 (Analyzing), as demonstrated by the t-value of 5.749. For social studies teachers and curriculum designers around the world who are looking for workable and quantifiable ways to address the persistent crisis in critical thinking abilities, this is an important discovery. Nonetheless, a number of pertinent findings, such as those from Suwanda et al. (2023), highlight the significance of fostering critical thinking abilities in social studies education as a pressing need in the field of education. Another study by Martiarini, (2015) showed how mastering sentence structure and critical thinking techniques can enhance students' reading comprehension, which is linked to the growth of critical and cognitive skills through full sentence-based learning.

Three key conclusions were reached based on the data analysis and research findings. First, with an implementation rate of 79.33% (classified as "Good"), the Complete Sentence learning model was successfully implemented in the experimental class (VIII A). Students' cognitive engagement supported this implementation; 88.3% of them said the model enhanced their critical thinking abilities.
Second, students who used the Complete Sentence model (experimental class) showed a significant improvement in their critical thinking abilities when compared to those who received traditional instruction (control class). While the control class only saw an increase of +3.00 points (from 65.83 to 68.83), the experimental class's average score increased by +14.67 points (from 68.50 to 83.17). Third, the Independent Samples t-test results for hypothesis testing showed a statistically significant difference between the two groups (t = 5.749; Sig. = 0.000 < 0.05). These results demonstrate that the Complete Sentence learning model is much more successful than traditional approaches in helping students develop their critical thinking abilities, especially at the cognitive levels of C3 (Applying) and C4 (Analyzing). According to this study, the Complete Sentence model is a useful and quantifiable pedagogical intervention for improving higher-order thinking abilities in social studies instruction.