科

Left grain radical (Kangxi #115) — a pictograph of a stalk of grain bending under the weight of its ripe head. The indexing radical of 科. Carries the literal etymology: 科 originally meant measuring out grain with a 斗 dipper, the basis of imperial classification systems. Same radical anchors 秋 (autumn), 种 (seed), 稻 (rice), 移 (transplant) — the entire grain-and-harvest family.

Right 斗 — a pictograph of a long-handled dipper used as a unit of dry measure (about 10 升). Reinforces the meaning: 科 is etymologically 'measuring grain with a dipper', the act of sorting and grading harvests. By extension came 'category, branch, department, exam-classification' — every modern sense of 科 (科学 science, 科目 subject, 内科 internal medicine) traces back to 'sorting things into measured portions'.