Investigating the invisible: a STEAM inquiry sequence to foster systems thinking in microbiology

Microorganisms play an essential role in human health and ecosystem functioning, yet students often associate them exclusively with disease and have difficulty understanding their roles within biological systems. This article presents a STEAM teaching sequence for Grade 7 students (12–13 years old) that integrates microbiological inquiry, mathematical modeling, and statistical analysis to promote systems thinking and scientific literacy. Students investigate the presence of microorganisms in their school environment by formulating hypotheses, designing controlled experiments, culturing microorganisms on agar plates, and interpreting experimental evidence. While cultures are incubating, they conduct a statistical investigation of hygiene habits by collecting, organizing, and analyzing survey data using Microsoft Excel. The sequence concludes with a classroom scientific conference where students communicate their findings through scientific posters and oral presentations supported by peer assessment. Grounded in inquiry-based science education, STEAM integration, and systems thinking, the article describes the instructional sequence, required materials, assessment tools, and examples of students’ work to support classroom implementation. Although student learning outcomes are not analyzed, the proposed sequence provides teachers with a practical framework for engaging middle school students in interdisciplinary learning while fostering evidence-based reasoning, scientific communication, and a deeper understanding of microorganisms.