This lecture covers various methods for characterizing particle shapes and sizes, focusing on non-spherical particles and their measurement challenges. The instructor discusses the importance of equivalent spherical diameter and how it varies with different measurement techniques. The lecture highlights the significance of morphology in interpreting results, particularly for materials like kaolin and aluminum platelets. The instructor explains laser diffraction as a prevalent method for size distribution analysis, emphasizing the need for accurate imaging to complement measurements. Additionally, sedimentation techniques, including gravitational and centrifugation methods, are explored, detailing how particle size affects sedimentation rates. The lecture also addresses the complexities of measuring agglomeration and aggregation in powders, providing insights into the relationship between particle size, density, and porosity. The instructor concludes by discussing the importance of standardized protocols in obtaining reliable data for various applications, including ceramics and catalysis, and the necessity of thorough documentation in particle size characterization.