The study was conducted in Lagos State, Nigeria, which is administratively divided into six educational districts and operates under a national curriculum supervised by the Lagos State Ministry of Education. The Nigerian education system follows a 9-3-4 structure: nine years of free and compulsory basic education, three years of senior secondary schooling, and four years of tertiary education (Fafunwa, 2018). After completing basic and senior secondary education, students may pursue either technical education or university study, depending on their interests and career goals.

Participants were students transitioning from basic education to the first year of senior secondary school (SSS1) at a public high school in Educational District VI. At this level, students begin to engage with distinct academic disciplines, including chemistry, physics, and biology, alongside commercial and arts subjects, and are expected to specialize in one of three tracks: science, commerce, or arts. Participants in this study majored in science, were offered chemistry during the first term of the 2025 academic session and had no prior exposure to riddle-based learning, making them suitable for examining its instructional relevance. The age range of participants was 12 to 14 years. Students at the point of first exposure to chemistry are often discouraged by the perception that the subject is abstract and difficult to grasp; alongside mathematics, chemistry is widely perceived as a gateway to STEM disciplines at higher levels of education (Zhao, 2022). The present study accordingly targeted students who had opted for the science track, with the specific aim of examining their engagement in chemistry. A total of 34 SSS chemistry students participated, selected as an intact class; ethical approval and informed consent were obtained prior to data collection.

Ethical approval for the study was obtained prior to data collection from the relevant institutional and school ethics review authority, and permission to conduct the study was granted by the school administration in Educational District VI, Lagos State. Because participants were minors (12-14 years old), written informed consent was obtained from parents or legal guardians, and student assent was obtained directly from participants before the engagement questionnaire, achievement test, and reflection instruments were administered. Students were informed that participation was voluntary, that declining to participate would not affect their standing in the class, and that their responses would be anonymized. The classroom teacher, who administered the instruments as part of regular instruction, collected the paper-based responses and forwarded scanned copies to the first author; no student names or other identifying information were retained in the analytic dataset.

Riddle-based learning was implemented as a structured instructional strategy rather than as an isolated classroom activity. Riddles were deliberately integrated into regular chemistry lessons and aligned with the prescribed curriculum topics for the term. Each riddle was designed to introduce or reinforce key chemistry concepts by presenting them in metaphorical or problem-oriented forms that required reasoning and discussion. Riddles were generated using a generative artificial intelligence tool (ChatGPT-5) and subsequently reviewed by the classroom teacher and the researcher to verify content accuracy, curriculum alignment, and age appropriateness. This review process helped to ensure that the resulting riddles functioned as meaningful cognitive prompts rather than as entertainment devices. A sample of the riddle-modified syllabus is presented in Table 1.

Instruction was organized around the 5E instructional model (Bybee et al., 2006). Riddles were embedded in the engage and explore phases to stimulate curiosity, activate prior knowledge, and encourage collaborative learning, and in an application, phase drawn from the model’s elaborate stage, in which students solved mole problems and composed riddles of their own. The explain and evaluate phases proceeded as in conventional instruction and were not modified by the intervention. The teacher scaffolded instructions to support learning within students’ ZPD. Riddle-based activities were infused into the chemistry syllabus throughout the term, ensuring that students encountered them in every chemistry topic. Table 2 presents the three riddle-adapted phases.

A multi-method data collection approach was used to capture the association of riddle-based learning with students’ engagement and conceptual understanding. Riddles functioned as mediating tools within students’ ZPD, prompting dialogue, reflection, and collaboration. Data were collected through a student engagement survey, a pre-/post-test achievement test, and qualitative reflections from students and the classroom teacher.

The multi-method design allowed both quantitative and qualitative analytic approaches to examine the association of riddle-based learning with students’ engagement and conceptual understanding. Students’ engagement was analyzed using the Wilcoxon signed-rank test, and the achievement test was analyzed using a paired-samples t-test. Students’ responses to open-ended questions on dimensions of engagement were analyzed thematically to provide deeper insight into their learning experiences.

A Wilcoxon signed-rank test was conducted for each dimension of engagement; results are presented in Table 3.

To examine the association of riddle-based learning with students’ conceptual understanding, a paired-samples t-test was conducted; results are presented in Table 4.

The paired-samples t-test indicated a statistically significant difference between pre-test (mean [M] = 32.40, standard deviation [SD] = 14.22) and posttest conceptual understanding scores (M = 45.60, SD = 13.54), t(33) = -3.17, p = .003, dz = 0.54, representing a medium effect size. This result indicates a statistically significant increase in conceptual understanding scores over the intervention period. Excerpts from students’ reflections further corroborate this pattern. Students described the riddles as prompting deep thought about the mole concept and supporting their ability to solve chemistry problems:

The deep thought prompted by the riddles also appeared to help students make connections to prior knowledge related to new topics. One student explained:

Beyond drawing on prior knowledge, students indicated that the riddles helped them explain chemistry concepts in their own words rather than focus solely on producing a technically correct answer:

Taken together, the quantitative results and the pattern of student reflections suggest that riddle-based learning was associated with students’ engagement with chemistry concepts, giving them the opportunity to reflect on the topic, connect it to prior experience, and explain it in their own words.

The thematic analysis of the data further revealed challenges associated with implementing riddle-based instruction. Despite the associations reported above, students’ and the teacher’s reflections indicated that riddle-based learning was also associated with difficulties, including overthinking and spending considerable time on a single riddle. The following excerpts illustrate these difficulties:

As a result, some students expressed a preference for direct instruction over riddle-based tasks:

The teacher’s reflection likewise indicated that integrating riddles into chemistry instruction presented a genuine challenge for some students:

The teacher also noted that the deliberately tricky wording used in some riddles could work against comprehension:

These accounts suggest that riddles can be cognitively demanding in ways that are not uniformly productive, and that adequate teacher support is likely needed to help students move from a state of cognitive dissonance toward comfort and competence in resolving riddle problems.

Consistent with the quantitative results, students’ reflections indicated that riddles prompted “deep thinking” and sustained mental effort, both core indicators of cognitive engagement (Doolittle, 1995; Fredricks et al., 2004). This pattern aligns with a broader body of research suggesting that intellectually playful tasks, such as riddles, gamified instruction, and puzzles, are associated with deeper cognitive investment because they require learners to analyze, infer, and reason rather than passively recall information (Coelho et al., 2026; Fontes et al., 2024). It is also consistent with research indicating that learning activities introducing cognitive challenge without an immediate solution path can foster productive struggle in ways that support conceptual change and longer-term understanding (Kapur, 2016; Schonberg, 2025). The increased cognitive engagement observed here also reflects students’ active use of language to make sense of chemistry concepts, consistent with Vygotsky’s (1978) view that thought develops through speech and social interaction; students’ reports that riddles made them “think deeply” and “reason” suggest that riddles externalized thinking that students later internalized as individual understanding.

Behavioral engagement also increased, with students reporting greater participation, attentiveness, and collaborative problem-solving during riddle-based lessons. This finding is consistent with prior research suggesting that riddles and problem-based prompts encourage active classroom behaviors, particularly discussion and peer interaction (Prince, 2004), and with the general pattern that students who perceive a task as an intriguing challenge, rather than a routine exercise, are more likely to take initiative and persist. In chemistry specifically, interactive strategies that emphasize sense-making have been associated with greater willingness to participate and articulate ideas publicly (Cooper et al., 2018). This pattern resonates with Vygotsky’s (1978) concept of the ZPD, the distance between what learners can do independently and what they can accomplish with guidance from more capable peers or instructors. During the riddle-based activities, students collaboratively explored possible solutions, shared partial understanding, and refined ideas through discussion, positioning the riddles within students’ ZPD by offering challenges that were initially difficult but solvable through social mediation and scaffolded instruction. The teacher’s observation that previously inactive students became more involved when riddles were introduced is consistent with this interpretation: shared intellectual responsibility, from a socio-cultural perspective, can draw students into participation who might otherwise remain passive, by creating a shared problem space that allows students to contribute ideas without fear of immediate evaluation.

Emotional engagement showed a similar pattern, with some students describing the riddle-based lessons as more enjoyable and motivating than traditional instruction. These responses are consistent with research suggesting that playful intellectual activity promotes curiosity and positive affect, which can in turn support attention, subject interest, and learning (Hidi & Renninger, 2006; Pekrun et al., 2011). From a socio-cultural perspective, students’ reports of curiosity and enjoyment suggest that the riddles reframed chemistry learning as a socially supported intellectual challenge rather than an individual performance task; the supportive classroom discourse surrounding riddle-solving appeared to foster a sense of belonging and confidence that socio-cultural theorists consider important for sustained participation in learning communities. Students’ ability to explain concepts “in their own words” is also consistent with the process of internalization Vygotsky (1978) described, whereby socially mediated language gradually becomes internal speech supporting independent reasoning.

The study also found a statistically significant increase in students’ conceptual understanding following the intervention, a pattern consistent with research indicating that learning tasks requiring explanation, reasoning, and connection to prior knowledge support meaningful learning in science (Chi & Wylie, 2014; Vosniadou, 2013). Students’ reflections suggested that riddles helped them activate prior knowledge and reason through chemical ideas and explain concepts in their own words. Related patterns have been reported in studies using riddles, analogies, or conceptual puzzles to support understanding in chemistry and physics, with associated gains in conceptual clarity and problem-solving performance (Adzape et al., 2020; Huang et al., 2020; Lathwesan & Belova, 2021). Collectively, these findings are consistent with the view that riddle-based learning functions as a form of cognitively activating instruction associated with engagement and conceptual understanding, positioning students as active sense-makers who bridge abstract chemical concepts and their existing cognitive frameworks.

Alongside its apparent benefits, riddle-based learning was also associated with notable challenges, a pattern that itself aligns with socio-cultural theory: students who experienced frustration or cognitive overload may have encountered tasks that exceeded their ZPD because scaffolding was insufficient for their needs. Some learners reported overthinking, cognitive fatigue, frustration, and even dislike for riddles, particularly when riddles were perceived as excessively demanding or time-consuming. These experiences are consistent with cognitive load theory, which suggests that tasks requiring high levels of reasoning can overwhelm learners when scaffolding is inadequate (Sweller et al., 2011); when riddles contain complex or misleading language, students may focus on irrelevant details rather than core concepts, increasing extraneous cognitive load. This pattern is consistent with prior cautions in the science education literature that, while productive struggle can support learning, unstructured or poorly supported challenge can instead lead to disengagement, especially among students with lower prior knowledge or confidence (Kapur, 2016; Kirschner et al., 2006). The teacher’s reflection illustrates this tension, noting that some students struggled to connect ideas within riddles or resisted the approach because they associated it with excessive mental effort, a pattern consistent with prior findings that students accustomed to teacher-centered instruction may initially resist inquiry-oriented approaches requiring sustained thinking (Brown et al., 2012). Together, these findings suggest that riddles are most effective when thoughtfully designed and strategically facilitated, with teachers playing a critical role in moderating cognitive demand, clarifying task goals, and supporting students as they move from initial confusion toward understanding (Belland et al., 2017; Hmelo-Silver et al., 2007).

These findings suggest that riddle-based learning may be a useful tool for supporting students’ engagement and conceptual understanding in chemistry classrooms. By drawing on metaphor, dialogue, and problem-solving, riddles offer an accessible pathway into scientific thinking that does not require specialized materials or technology, an important consideration in resource-constrained classrooms. Riddles appear most effective when teachers intentionally support students’ movement from confusion to understanding, ensuring that challenges remain within what students can reasonably process, given appropriate scaffolding. Used in this way, riddles may function as tools for social meaning-making that support both engagement and conceptual understanding. The study adds to a growing body of work advocating creative, inquiry-oriented strategies in chemistry teaching, and is broadly consistent with the view that cognitive development is socially mediated and culturally shaped. As such, riddle-based learning holds promise not only to support students’ conceptual understanding but also to inform how science is taught and experienced in the classroom.

This study has several limitations that should be considered when interpreting its findings. First, and most importantly, the study used a single-group pre-/post-test design without a comparison or control group. While this design was appropriate given the ethical and logistical constraints of intervening in an intact classroom, it does not support causal inference about the specific effect of riddle-based learning. Several threats to internal validity cannot be ruled out: maturation, in that students’ natural cognitive development or growing familiarity with course content over the term may partly account for the observed gains; instructor effects, in that the classroom teacher’s general enthusiasm, skill, or attention, rather than the riddles specifically, may have contributed to the results; and testing or practice effects, in that scores may have improved partly because students had already encountered the pretest items. Accordingly, all findings reported here should be interpreted as associations between riddle-based learning and engagement and conceptual understanding, rather than as evidence of a causal effect.

Second, the sample was small (N = 34) and drawn from a single intact classroom in one school within one educational district in Lagos State, which limits statistical power and the generalizability of the findings to other schools, regions, or educational systems. Third, engagement and reflection data relied on students’ self-reports, which may be subject to social desirability bias, particularly given that the classroom teacher was involved in both instruction and data collection.

Future research should replicate this study using a comparison or control-group design, ideally with random assignment at the classroom level, to strengthen causal inference regarding the specific effect of riddle-based learning. Longitudinal designs tracking engagement and conceptual understanding across a full academic year, or across multiple chemistry topics beyond the mole concept, would help clarify whether the associations observed here persist over time and generalize across content areas. Future work should also examine how different levels and forms of teacher scaffolding moderate whether riddles produce productive cognitive challenge rather than disengagement or frustration, given the difficulties evident in the data.

Author contributions: MM: conceptualization, data curation, formal analysis; BMA: writing – review & editing; JIS: formal analysis. All authors agreed with the results and conclusions.

Funding: No funding source is reported for this study.

Ethical statement: The authors confirm that this study was conducted in full compliance with the ethical standards of the American Psychological Association. Ethical approval was obtained prior to data collection, informed consent was secured from all participants and their guardians, participation was voluntary, and all data were anonymized to protect participants’ identities. The authors confirm that all processes were carried out in accordance with all applicable rules and guidelines with the Virginia Tech IRB approval number 24-1179. All participants consented to participate in the study.

AI statement: In the preparation of this manuscript, ChatGPT version 5.0 was utilized to enhance language quality, specifically for grammatical corrections, and for generation of riddles. Subsequently, the generated riddles were reviewed by the chemistry teachers and the first author.

Declaration of interest: No conflict of interest is declared by the authors.

Data sharing statement: Data supporting the findings and conclusions are available upon request from the corresponding author.