Final answer:
Sand has the largest grain size when compared to silt and clay, and determining grain size is key in classifying sediment in geology.
Step-by-step explanation:
Out of sand, silt, and clay, sand has the biggest grain size. Sand particles are larger and more distinct compared to the much finer particles of silt and clay. Sediment grain size is commonly measured by geologists to help classify and describe sediment through methods such as sieving and using devices known as particle size analyzers. Understanding the grain sizes is essential as it provides insights into the sediment's transport and depositional history. A common visual representation geologists use for different proportion of these components is the triangular or ternary plot, which helps in identifying the type of sediment or soil based on its composition.