The eight Tiantai classifications of Śākyamuni's teaching, from the Avatamsaka to the Lotus and Nirvāna sūtras, divided into the two sections (1) 化法四教 his four kinds of teaching of the content of the Truth accommodated to the capacity of his disciples; (2) 化儀四教 his four modes of instruction. (1) The four 化法教 are: (a) 三藏教 The Tripitaka or Hīnayāna teaching, for śrāvakas and pratyekabuddhas, the bodhisattva doctrine being subordinate; it also included the primitive śūnya doctrine as developed in the Satyasiddhi śāstra. (b) 教通His later "intermediate" teaching which contained Hīnayāna and Mahāyāna doctrine for śrāvaka, pratyekabuddha, and bodhisattva, to which are attributed the doctrines of the Dharmalaksana or Yogācārya and Mādhyamika schools. (c) 別教 His differentiated , or separated, bodhisattva teaching, definitely Mahāyāna. (d) 圓教 His final, perfect, bodhisattva, universal teaching as preached, e.g. in the Lotus and Nirvāna sūtras. (2) The four methods of instruction 化儀 are: (a) 頓教 Direct teaching without reserve of the whole truth, e.g. the 華嚴 sūtra. (b) 漸教 Gradual or graded, e.g. the 阿含, 方等, and 般若 sūtras; all the four 化法 are also included under this heading. (c) 祕密教 Esoteric teaching, only understood by special members of the assembly. (d) 不定教 General or indeterminate teaching, from which each hearer would derive benefit according to his interpretation.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

化法四教與化儀四教，合稱為八教。化法四教是三藏教、通教、別教、圓教，因此四教是教化眾生的法門，故名化法；化儀四教是頓教、漸教、秘密教、不定教，因此四教是教化眾生的儀式，故名化儀。以上八教，都是天台宗所立。

陳義孝編, 竺摩法師鑑定, 《佛學常見辭彙》

（名數）台家所立之八教也。於華嚴時乃至法華涅槃時五時所說，化法之四教與化儀之四教是也。化法之四教者：一、三藏教，經律論之三藏，部類判然，說因緣生滅之四諦，正教聲聞緣覺之二乘，傍化菩薩者。二、通教，說即空無生之四真諦，使通三乘而同學者，但以菩薩為正機，二乘為傍機。三、別教，於二乘之人皆不同，別對菩薩說大乘無量之法者。四、圓教，對最上利根之菩薩說事理圓融之中道實相者（別圓二教之相違唯隔歷二圓融耳）。以上之四教，為化益眾生之法門，故名化法。化儀之四教者，以彼化法說示眾生之儀式作法也。一、頓教，對頓大之機，頓說別教圓教之大法者，如華嚴時是也。二、漸教，對漸機，漸漸次第說化法之四教，如鹿園方等般若三時之說相是也。三、秘密教，對一種之機，說秘密之法，使一會之人自他互知者，是由如來身口意之不思議力。四、不定教，於一會之中說一法使聞者異解，或得益或不得益者。蓋化法之四教，如藥味，化儀之四教如藥方，合成八教也。止觀義例曰：「頓等四教，是佛化儀；藏等四教，是佛化法。」

丁福保《佛學大辭典》