Radical 丨
6 strokes
師
knife 刂 (74a) + encompass 帀 (428a) = master 师
老师 (264) lǎoshī teacher
[教师 (265) jiàoshī teacher]

(At the murder crime scene) They drew a chalk line round the body which encompassed the knife he was holding — they would need a master detective to solve this. / The giant spotted a blood-soaked shillelagh on top of a wardrobe (“I didn’t need to be a master detective to spot this,” he said).