A recent study in the Journal of Chemical Education by Amanda M. A. Feu and colleagues investigated the effectiveness of a teaching method called Problematized Experimental Activity (PEA) using the context of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More as a sustainable soil conditioner. This approach aimed to enhance undergraduate chemistry students’ understanding of chemical concepts by having them engage in a real-world problem related to agricultural chemistry. The research took place with students at the Federal University of Espírito Santo, where they performed experiments to determine a red-yellow Oxisol soil’s active acidity, potential acidity, exchangeable aluminum, and available phosphorus. The team employed a qualitative analytical methodology known as Grounded Theory (GT) to interpret the students’ written responses and final products, such as their biochar production protocols.

The PEA method differentiates itself from traditional laboratory instruction by focusing on complex problem-solving rather than simply following a fixed set of steps to achieve an expected outcome. In this study, the guiding problem was to define production parameters for biochar that would be suitable for the specific soil needs, based on the results of their chemical analysis. While the students did not use biochar directly in their experiments due to logistical and technical constraints, they explored its effects theoretically and designed a production protocol based on their soil characterization results and a literature review. This approach was designed to help students connect their theoretical knowledge with practical skills, fostering autonomy, critical thinking, and interdisciplinary connections.

The qualitative assessment using GT revealed significant student learning in several key areas. Students not only developed essential laboratory skills, such as calibrating a pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More meter and constructing spectrophotometry calibration curves, but they also demonstrated a deeper conceptual understanding of the techniques they used. For instance, they were able to interpret how different solutions like water, calcium chloride (CaCl2​), and potassium chloride (KCl) influenced pH measurements by causing ion exchange and other buffering effects. They also understood the chemical principles behind titrimetric procedures for determining potential acidity and exchangeable aluminum, as well as the complexation reactions and instrumental principles of UV-vis spectroscopy used for phosphorus determination.

A notable finding was the students’ ability to link these analytical techniques to their course syllabus topics. For example, they connected the determination of active acidity with the halogen family due to the use of chloride salts in the soil suspensions, and phosphorus determination was linked to the phosphorus family. This contextualized learning strategy proved effective in fostering a deeper understanding and encouraging students to apply chemical concepts to real-world scenarios. Moreover, the study highlighted the positive impact of framing the activity around sustainability. Students frequently discussed the environmental benefits of biochar, such as using it for waste management and climate change mitigation through carbon sequestration. This demonstrates how the PEA method can cultivate not only scientific knowledge but also environmentally conscious thinking.

In conclusion, this research supports the use of the Problematized Experimental Activity as a valuable pedagogical tool for chemistry education. It shows that by integrating experimental learning with a contextualized, real-world problem, students can develop a comprehensive understanding of scientific concepts and practical skills. While the absence of a direct biochar application was a limitation, it provided a rich theoretical foundation and highlighted the importance of carefully designed teaching strategies that promote critical thinking and a connection to broader environmental issues. This approach offers a replicable framework for educators to create engaging, meaningful learning experiences that prepare students to address complex, real-world challenges. Sources

Source: Feu, A. M. A., Welsing, G. L., da Silva, A. L. S., Luz, P. P., & de Moura, P. R. G. (2025). Teaching Soil Chemistry through Problematized Experimental Activity: Determination of Acidity, Exchangeable Aluminum, and Available Phosphorus in Soils. Journal of Chemical Education, 10.1021/acs.jchemed.5c00027.