The second textbook exercise contrasts three patterns.
Word / formMeaning / explanation
أَعْلَمُونَafʿalūna, masculine sound plural: men more knowledgeable.
سُمْعَيَاتٌfuʿlayāt, feminine sound plural: women who hear more.
أَضَارِبُafāʿil, masculine broken plural: a paradigmatic form of people who strike more.
The word's first letter alone will not identify the form. The endings -ūna and -yāt, and the internal alif of afāʿil, identify different plural formations.