The concept of citizen science dates back to 1995, when Alan Irwin defined it as a paradigm in which scientists and the public collaborate to set research objectives in the United Kingdom. Around the same time, Rick Bonney applied it to projects at the Cornell Lab of Ornithology (USA), involving the public in avian research. Since then, more recent definitions have emerged, particularly those promoted by government and public policy organizations emphasizing citizen participation in the generation of scientific knowledge (Hecker et al., 2018; Raya, 2023).

According to Programa de las Naciones Unidas (2023), citizen science is a collective, participatory, and open effort to generate scientific knowledge driven by actors who do not necessarily belong to academia. This approach contributes to development by strengthening territorial activism, influencing agendas and public policies, fostering innovative solutions, and raising social awareness.

Existing systematic reviews have addressed citizen science from both educational and general perspectives. Aripin et al. (2023), through a PRISMA-based review, demonstrate that citizen science projects contribute positively to science learning at the school and university levels, particularly in terms of motivation, self-efficacy, inquiry skills, and environmental awareness. In contrast, Ilhami et al. (2024) report that recent citizen science research has focused primarily on environmental topics such as pollution and conservation, while studies centered on educational contexts and on the participation of teachers and students remain limited, which supports the need for more focused analyses within the educational domain.

Although citizen science has primarily been applied in biology, its integration into chemistry is still limited but promising. Engaging students in real research activities can enhance motivation, scientific literacy, and understanding of the role of science in daily life (Urválková and Janoušková, 2019). Teaching Chemistry and Biology at secondary and university levels develops transversal competencies such as critical thinking, problem-solving, scientific communication, and understanding of science’s social impact (Constable et al., 2021).

Schneiderhan-Opel and Bogner (2020) note that citizen science increases interest in biology by involving participants in real scientific processes such as sampling and species identification, fostering engagement with biological issues. Citizen science projects enrich biology courses by offering field experiences where students collect data and directly interact with biological components. This combination of research and active learning strengthens the understanding of the scientific method and connects theory and practice (Lichti et al., 2021).

Chemistry offers a powerful lens to understand both natural and technological phenomena, focusing on the composition, structure, and transformation of matter. Teaching in this field supports the interpretation of biological processes, the development of innovative technologies and products, and informed decision-making in areas such as health, environmental protection, and energy (Araújo et al., 2024). Yet, because many students view chemistry as abstract, connecting its content to real-world contexts through contextual learning approaches becomes crucial to foster scientific practice and critical thinking (Araújo et al., 2023).

Biology, on the other hand, positions educational institutions as key actors in species conservation, particularly for endemic or endangered organisms, through both research initiatives and public engagement. Tackling biodiversity loss and the impacts of climate change demands integrative strategies that combine scientific knowledge with community involvement (Chen and Sun, 2018). Furthermore, equipping students with applied skills in managing biological invasions prepares them to address environmental threats and meet the needs of universities, government agencies, and conservation organizations (Davies et al., 2016).

In Australia, Quinnell et al. (2023) studied citizen science projects that combine biology and chemistry, such as the Environmental Recovery Project, which uses iNaturalist to monitor species affected by wildfires, and CampusFlora, designed to increase awareness of plants and botanical literacy within university communities. Other projects integrate the synthesis of molecules with potential antimalarial activity, combining hands-on chemistry learning with advanced health research. These initiatives promote ecological and biological literacy, strengthening the connection between scientific theory and practice.

Henter et al. (2016) highlight projects that directly combine Chemistry and Biology, such as Mosquito Malaise Trap, in which participants collect and analyze insects through DNA barcoding; BioTrails, focused on identifying marine and terrestrial species in national parks; and School Malaise Trap, which integrates insect collection and sequencing to work with real data. All these studies show that citizen science contributes to the development of scientific competencies, fosters interest in the natural sciences, and facilitates the resolution of real environmental problems through collaboration among students, communities, and scientists.

Citizen science projects thus offer both educational and research benefits. Their integration into formal education enables students to participate in authentic scientific tasks using real data and tools, while fostering interest in science even among lower-performing students (Silva et al., 2016). However, many students interested in STEM areas such as biology, chemistry, environmental sciences, and engineering do not always demonstrate a solid knowledge base, highlighting the need for educational strategies that provide practical experiences and innovative methodologies to strengthen sustainable scientific vocations (Musavi et al., 2018).

Existing studies show that citizen science projects in educational contexts have been developed predominantly within the field of Biology, while applications in Chemistry have received comparatively less attention. However, to date there is no systematic synthesis that jointly examines how these two disciplines are integrated into citizen science projects for educational purposes. Given that Chemistry and Biology share experimental, methodological, and applied approaches, their joint analysis allows for a better understanding of how citizen science contributes to the development of scientific competencies and problem-based learning grounded in real-world contexts. This review addresses this gap by specifically examining educational citizen science projects in Chemistry and Biology, distinguishing itself from broader syntheses focused on science education in general, and providing a focused perspective on the thematic areas addressed, participation profiles, and the links between learning and social and environmental benefits.

Based on this situation, the present study aims to analyze how Chemistry and Biology can be implemented in citizen science projects to improve student learning and generate social contributions. To achieve this, the following research questions are posed:

Two major scientific databases were selected: Scopus and Web of Science, both recognized for their broad coverage and the quality of indexed studies. In the case of Web of Science, the Emerging Sources Citation Index was excluded because these journals are still in the process of consolidation and may not yet meet the visibility and quality standards required for this study.

Eligibility criteria included studies published in any language that contained the main research terms in the title, abstract, or keywords. The search was limited to publications from the last 10 years and considered journal articles, conference papers, reviews, and book chapters. This selection ensured that the data collected were recent, relevant, and of verified academic quality.

The search strategy began with Scopus, using the main research keywords. The results obtained were analyzed in RStudio (version 4.4.2) with the biblioshiny package, allowing for a bibliometric analysis of the studies and the detection of additional relevant related terms that may have been initially overlooked (see Figure 1).

The final search string was executed on August 5, 2025, and the procedure was repeated twice to ensure the inclusion of the most relevant terms related to the study’s topic. In each database, filters were applied according to the previously established eligibility criteria, restricting the search to titles, abstracts, and keywords, and considering only studies published within the last 10 years (see Table 1).

In the first stage, all records retrieved from Scopus and Web of Science were consolidated, yielding a total of 283 studies. Duplicate entries were then removed, resulting in 176 unique documents; most duplicates originated from Web of Science, corresponding to 107 studies already indexed in Scopus. Subsequently, titles, abstracts, and keywords were screened to exclude records not directly related to the research topic. Eight additional documents were excluded due to the lack of access to the full text.

The remaining studies underwent a methodological risk of bias assessment, using adapted criteria according to the type of research, with the aim of including only those with a low risk of bias. The entire review process—including screening, eligibility assessment, and decision-making—was conducted collaboratively by the research team. Any discrepancies were resolved through consensus discussions, ensuring objectivity, transparency, and consistency in the selection of studies.

Ultimately, 84 studies met the quality, thematic relevance, and methodological rigor criteria, constituting the final dataset analyzed in this systematic review. This procedure is summarized in Figure 2, which follows the PRISMA flow diagram.

The risk of bias assessment was conducted systematically and across multiple stages throughout the review process, with the aim of ensuring methodological rigor and the reliability of the included studies. In an initial phase, explicit inclusion and exclusion criteria were defined to select studies that were both relevant and methodologically sound. As part of this process, emerging journals indexed in Web of Science were excluded, as their stage of editorial consolidation might not yet guarantee homogeneous standards of methodological quality for the purposes of this review.

Subsequently, a quality and risk of bias assessment approach based on adapted Cochrane domains was applied, acknowledging the heterogeneity of the study designs included. Prior to the assessment, studies were classified according to their design, including original research articles, methodological studies, theoretical and conceptual studies, review articles and systematic reviews, as well as case studies. This classification allowed the evaluation criteria to be tailored to the methodological characteristics of each study type, avoiding the uniform application of non-pertinent domains.

The risk of bias assessment focused primarily on methodological transparency, clarity of procedures, integrity of the reported data, and coherence between objectives, methods, and results. Domains traditionally associated with experimental trials, such as random sequence generation, allocation concealment, or blinding, were adapted or excluded when not applicable to educational, observational, or mixed-methods studies. Studies presenting substantial methodological inconsistencies, absence of critical information, or deficiencies that prevented an adequate evaluation of their development or results were classified as having a high risk of bias.

The complete quality assessment process, including the specific criteria applied to each study design and the individual results of this evaluation, is documented in detail in the Excel file provided as Supplementary material, ensuring transparency and traceability of the procedure.

Study screening and selection were conducted by all five authors, who were actively involved in all stages of the process. In the first stage, titles, abstracts, and keywords were independently screened by two authors in each case, with studies distributed equally between reviewer pairs (50% per pair). In the second stage, full-text assessment followed the same procedure. In cases of uncertainty or disagreement regarding study eligibility, a third author intervened to reach a final decision by consensus, thereby strengthening the reliability and consistency of the selection process.

To synthesize the results, relevant data were first extracted from each study, focusing on characteristics, key findings, and statements that directly addressed the research questions. These data were organized into a Microsoft Excel matrix, providing a structured visualization of the information and facilitating subsequent analysis. Since the responses and extracted information were not uniform across studies, the data were then classified and grouped into thematic categories. This approach made it possible to cluster similar elements and generate a coherent framework that clearly and concisely summarized the most relevant findings.

The analysis of the number of publications over the last 10 years reveals a steady increase until 2018 (see Figure 3), followed by a brief stabilization during 2019–2020 and a marked peak in 2021, likely associated with the momentum generated by the pandemic. Although production decreased afterward, it remained above initial levels, reflecting the consolidation of the topic as a research line. The decline observed in 2025 is probably due to incomplete data for the current year.

Figure 4 shows the geographical distribution of publications on citizen science projects in Chemistry and Biology. The highest concentration is found in the United States, followed by several countries in Europe and Oceania. In contrast, production in Latin America, Africa, and much of Asia is scarce or even absent. This pattern reveals a pronounced concentration of research activity in regions with greater scientific infrastructure, highlighting persistent inequalities in the generation and dissemination of knowledge in this field.

Understanding the themes addressed in citizen science projects is essential for the educational community, researchers, and society at large to identify potential areas of application within their institutions or communities. This information helps guide the implementation of projects based on Chemistry and Biology, contributing to the integration of these disciplines into meaningful learning experiences that foster the development of scientific competencies and address local issues (see Table 2).

The results indicate that most of the analyzed citizen science projects are primarily related to Biology, while Chemistry shows a more limited, yet contextually significant application. Among the biological topics, the most frequent are linked to human health, biodiversity, and ecology, including studies on species conservation, environmental monitoring, climate change, entomology, and zoology.

In the case of Chemistry, projects mainly focus on water quality and pollution, encompassing physicochemical analyses, detection of metals, bacteria, and microplastics, as well as air quality assessment and the study of biogeochemical cycles in soils and ecosystems. Although Chemistry has a smaller presence, there are thematic intersections between the two disciplines, particularly in studies on environmental pollution and aquatic ecosystem analysis. In these contexts, the integration of chemical and biological methods enables a more comprehensive understanding of the investigated problems.

Biodiversity emerges as the most recurrent theme in the reviewed studies, especially regarding the conservation of animal and plant species and ecosystem monitoring. This trend reflects growing concerns about sustainability and environmental education. Another relevant finding is the diversity of methodological approaches, which range from direct observation and monitoring to molecular analyses and public health studies. This variety demonstrates the breadth and potential of citizen science projects to generate applied knowledge and connect Chemistry and Biology education with real-world societal challenges.

Citizen science projects engage a wide range of participants whose composition and characteristics directly shape the dynamics and outcomes of these initiatives (Figure 5). Identifying participant profiles makes it possible to recognize the educational levels and contexts in which the projects take place, as well as how students and communities contribute to learning processes and the generation of scientific knowledge. This information is crucial for understanding how citizen participation can be effectively integrated into Chemistry and Biology education.

The literature shows that secondary school students represent a key participant group in citizen science projects, taking part throughout their entire educational trajectory, with particular engagement in Biology, Chemistry, Mathematics, and Environmental Science courses (Aivelo, 2023; Araújo et al., 2022, 2023; Christ et al., 2022; Collier et al., 2023; Dalgarno et al., 2018; Estallo et al., 2024; Ezran et al., 2017; Henter et al., 2016; Moore et al., 2020; Schneiderhan-Opel and Bogner, 2020; Silva et al., 2016; Weisberg et al., 2023). This group includes students with disabilities and those enrolled in high school diploma programs (Ruiz Whalen et al., 2025). They are frequently involved in data collection, observation, and biodiversity monitoring activities.

In higher education, university students also participate in citizen science projects, particularly those enrolled in undergraduate programs in biology, environmental sciences, food biotechnology, and other fields related to the natural sciences (Brevik et al., 2022; Golumbic and Motion, 2021; Larkin et al., 2024; Lichti et al., 2021; Messager et al., 2022; Rosenthal et al., 2024; Vance-Chalcraft et al., 2021; Webber et al., 2021). Typically participating in both introductory and advanced courses in biology, chemistry, and biotechnology, these students contribute not only to data collection but also to data analysis, applying the theoretical knowledge gained through their studies.

In addition, postgraduate, master’s, and doctoral students, particularly in areas such as molecular biology, analytical chemistry, and biotechnology, participate in citizen science projects that involve more complex research activities, including data analysis, laboratory work, and the application of specialized techniques (Davies et al., 2016; D’Eon et al., 2021; Quinnell et al., 2023).

The general public, including families (Estallo et al., 2024), citizen volunteers, and individuals with an interest in nature and conservation, also plays an active role, typically without requiring specialized training (Bakker et al., 2020; Gassett et al., 2021; Lindermann et al., 2024; Pernat et al., 2024; Salomé-Díaz et al., 2023). These participants engage in observation, data collection, and educational activities focused on citizen science. Many projects are intentionally designed to be inclusive and accessible, enabling people with no prior experience to participate effectively (Smith et al., 2023).

The literature also indicates that teachers and educators at secondary and higher education levels assume the role of guiding and coordinating activities (Araújo et al., 2023, 2024; Ellenburg et al., 2019; Krach et al., 2018; Ruiz Whalen et al., 2025). Additionally, researchers and professionals in ecology, biology, chemistry, and environmental sciences participate in project supervision and applied research, while specialized volunteers (Davies et al., 2016; Ganzevoort et al., 2017; Gassett et al., 2021; Lucrezi et al., 2018; Odom and Benedict, 2018; Rey-Suárez et al., 2025)—such as those with training in biology or scuba diving (Das et al., 2019; Roelfsema et al., 2016)—contribute their expertise to conduct more technical studies, particularly in marine environments.

The application of Chemistry and Biology to real-world problems through citizen science projects is observed in studies focused on public health, food safety, and environmental conservation. These projects address activities related to contaminant detection, food analysis, ecosystem monitoring, and the collection of environmental and biological data. Table 3 presents a synthesis of the specific applications of Chemistry and Biology across different contexts and the activities carried out in each case.

One of the main challenges in citizen science projects is ensuring data quality and reliability (Berglund et al., 2023; Frigerio et al., 2018; Mitchell et al., 2017; Reed et al., 2018; Roelfsema et al., 2016; Salomé-Díaz et al., 2023). Common issues include species misidentification, geographic bias, and participants’ limited knowledge (Aivelo, 2024; Lindermann et al., 2024; Paradise and Bartkovich, 2021; Pernat et al., 2024). A lack of standardized methods, validated protocols, and centralized repositories (Chen and Sun, 2018; Gassett et al., 2021), combined with the reliance on low-cost tools, reduces the reliability of results and limits their scientific and educational value (Dalgarno et al., 2018; Roelfsema et al., 2016). These difficulties are compounded by traditional, lecture-based teaching methods that focus on rote memorization, making it harder to foster motivation, active participation, deep scientific understanding, and meaningful learning assessment (Ellenburg et al., 2019; Harris and Ballard, 2021; Mioni, 2022).

Logistical and resource limitations also present a significant barrier. The scarcity of laboratories, infrastructure, funding, and specialized personnel affects the sustainability and continuity of projects in both urban and rural contexts (Aivelo, 2024; Bliese et al., 2020; Collier et al., 2023; Ezran et al., 2017; Gassett et al., 2021; Ruiz Whalen et al., 2025; Taylor et al., 2024). Coordinating activities and integrating them into the curriculum can be complex, often preventing students from effectively connecting projects to academic content and relevant practical experiences (Davies et al., 2016; Peltoniemi et al., 2023; Rode and Torkar, 2023).

Another major challenge involves motivation and participation. Student and volunteer engagement depends on their perception of project relevance, recognition of their contributions, and the extent to which the initiatives address real-world problems (Aivelo, 2024; Chen and Sun, 2018; Lüsse et al., 2022). Furthermore, equity, inclusion, and cultural diversity must be considered, requiring adapted strategies that foster the participation of diverse groups and connect science with meaningful social and ethical contexts (Anthony et al., 2023; Golumbic and Motion, 2021; Mitrache, 2024).

Finally, insufficient training for both participants and teachers limits scientific literacy, data analysis skills, and the effective use of appropriate didactic methodologies (Davies et al., 2016; Rode and Torkar, 2023). While technological tools can be useful, they often face issues of accessibility, accuracy, and feedback. This highlights the need for intuitive interfaces, adequate resources, and structured support to ensure effective and reliable learning experiences within citizen science projects (Dalgarno et al., 2018).

Chemistry and Biology play a fundamental role in citizen science because they enable the understanding, analysis, and resolution of environmental, health, and social problems through active community participation. These disciplines provide the conceptual and methodological tools to identify contaminants, study ecosystems, monitor biodiversity, understand biological processes, and assess chemical risks. Although volunteer data collection, such as water sampling, soil analysis, or species identification, may present precision limitations, it generates valuable information that complements traditional scientific studies and expands research coverage to broader geographic areas and more diverse populations.

In addition, citizen science projects promote hands-on learning of Chemistry and Biology concepts by fostering skills related to observation, analysis, data interpretation, and critical thinking. Students and citizens develop scientific and epistemological competencies that go beyond theoretical knowledge, learning to relate natural and chemical phenomena to real-world problems in their local contexts. This direct connection between knowledge and application strengthens motivation, interest in science, and the ability to participate in an informed manner in environmental and public health decision-making.

In a broader context, the integration of Chemistry and Biology in these projects contributes to sustainable and social development by providing tools to address environmental challenges, conserve natural resources, improve water and air quality, and promote inclusive science education. It also strengthens scientific citizenship by involving diverse actors in research, fostering collaboration among educational institutions, communities, and scientists, and raising awareness of the importance of science in addressing collective problems.

Therefore, the relevance of these disciplines is reflected in their capacity to inform evidence-based policies and practices. Data generated through citizen science projects, despite their limitations, help guide local and national decisions in health, conservation, and education, strengthening the relationship between scientific research, learning, and social development. In this way, Chemistry and Biology are not only relevant for academic training and scientific knowledge, but also become strategic tools for sustainable progress and societal participation in the development of solutions to complex problems.

The findings of this study highlight the significant potential of integrating citizen science into Chemistry and Biology education to strengthen academic training, promote scientific literacy, and raise awareness of environmental and social issues from an early age. The active participation of students, teachers, and communities fosters analytical skills, data interpretation, and critical thinking, while encouraging collaboration and engagement with scientific research. From a practical perspective, these initiatives can be incorporated as innovative pedagogical tools by designing projects that directly link curricular content with local, environmental, and public health challenges, adapting objectives and methods to different educational levels and participant profiles.

In terms of future research, there is considerable scope to explore the effectiveness of different citizen science models, including the use of emerging technologies, digital data collection platforms, and participatory methodologies that extend involvement beyond formal educational settings. It is also relevant to examine the influence of contextual factors, such as educational infrastructure, access to resources, and participant training on the quality and reliability of the data generated. Longitudinal studies could further assess the sustained impact of these initiatives on scientific understanding, student motivation, and community capacity to address social and environmental problems. This would contribute to the development of clear guidelines for the implementation of citizen science projects in diverse regions and contexts.

This study presents several limitations that should be taken into account when interpreting its findings. The systematic review relied on projects documented in the scientific literature, which may have excluded local or unpublished initiatives that also provide valuable evidence. The heterogeneity in the quality and level of detail of the reported information made it difficult to conduct consistent comparisons across projects and to accurately assess the role of participants according to their educational profiles.

Additionally, Chemistry-related applications were less represented than those in Biology, which limited the analysis of their potential contribution to addressing social and environmental problems. The lack of longitudinal follow-up further restricted the ability to assess the sustained effects of citizen participation on scientific literacy, knowledge generation, and problem-solving in different contexts. These limitations point to important opportunities for future research, particularly in curricular integration, participant training, and the long-term impact assessment of citizen science initiatives.