“Journey to the Microcosmos: Preserving the History of the Microcosmos With Prepared Slides” explores how microscopes reveal rotifers, diatoms, and other microorganisms, and how prepared slides preserve these specimens for future observation. The video explains key microscopy concepts such as wet mounts, cover slips, mounting media, permanent slides, and specimen preservation, while also noting safety precautions like using a fume hood. It highlights the silicon shells of diatoms, the difference between living and preserved samples, and the role of 19th-century microscopy clubs and collectors in documenting the unseen world. Blending biology, scientific methods, and history of science, this content supports curriculum topics in microbiology, microscopy, museum collections, and observation-based inquiry. Part of the "Journey to the Microcosmos" series.