"ARC" is a model for analyzing and understanding the structure of any ESL lesson. "ARC" stands for "Authentic use," "Restrictied use," and "Clarification and focus." These categories form a pretty all inclusive partition of all possible language teaching activities. Lists of exactly which activity types fall into which categories are provided in the sections that follow this introduction. (Note: The material in this document is based on material in the book "Learning Teaching: A Guidebook for English Language Teachers" by Jim Scrivener (Heinemann, 1994), pp 133-138. This book doesn't cite where the ARC model ultimately comes from, so I can't tell you exactly where the model originated.)
The ARC model breaks a lesson down into a sequence of these three types of activities. For example, a CRRA lesson consists of the following sequence of activity types: 1. Clarification and focus; 2. Restricted use; 3. Restricted use; 4. Authentic use. Such a lesson might begin with examples of how to make and respond to polite requests, e.g. A: "Would you happen to have a ....?" B: "I'm sorry ....." (1) The students would then practice these patterns verbally in pairs making requests for different items or actions (2). This would be followed by the students individually writing their own dialogues of two or three conversational turns using the pattern (3). The use of language is restricted in step (3) because students must use the sentence patterns. However, they are free to create their own situations in which these patterns are used. Finally, they go around the classroom practicing the dialogues they have written with other students (4). The use of language in step (4) is authentic use because each student is confronted with new unpredictable situations as she interacts with other students. The student is forced to improvise a bit when she responds to the polite requests.
CRRA lessons emphasize the deduction or generation of new sentences from a pattern sentence. Students are given a pattern sentence (1) and they deduce new sentences from it (2,3). It has been referred to as a "Teach-Test" type of lesson plan. It is very similar to the PPP model (Present-Practice-Produce) type of lesson plan that is popular among teachers.
As Michael Lewis has emphasized in his book "The Lexical Approach" (LTP, 1993) students can also benefit from inducing or extracting patterns for themselves in an Observe-Hypothesize-Experiment (OHP) types of lessons. Deductive or PPP types of lessons are the not the only type that benefit students. An RCR type of lesson has more of an inductive pattern to it. It would consist of the following sequence of activity types: 1. Restricted use; 2. Clarification and focus; 3. Restricted use. Such a lesson might begin with a series of tape recorded polite requests, the students having to identify which are appropriate and which are inappropriate (1). The teacher then goes around the class noting down which mistakes were common and offers an explanation as to why those choices are wrong (2). A second set of similar tape recorded polite requests are played and the students are asked to identify which are appropriate (3). This time they are equipped with the explanation given in step (2) which should help them avoid mistakes. This type of lesson has a sort of feedback or review cycle built into it and has been referred to as a "Test-Teach-Test" type of lesson.
The same type of lesson might be done with an even more inductive, more open ended communicative activity (an Authentic use type activity) where the student has more opportunity to experiment with language of his own creation. The lesson pattern would then be ACA consisting of the following sequence of activity types: 1. Authentic use; 2. Clarification and focus; 3. Authentic use. This lesson type also has a feedback or review cycle built into it.
Other interesting points made in the book referred to above include:
a. CRRA is good for teaching points that are new to the students.
b. RCR is good if the students already "know something about the language item."
c. With RCR "the teacher is less likely to waste time telling students things they already know."
d. With CRRA "the teacher is able to plan his lesson around specific example sentences he has selected before the lesson."
The ARC model also has potential for helping teachers design "component"-like lessons that address particular teaching points (grammatical, lexical, functional/pragmatic) that can "plugged into" appropriate places in the syllabus. The ARC model could help teachers isolate exactly what goes into a successful lesson and incorporate this into a computer database that the teacher can use to clone an already existing lesson into a new lesson that addresses new teaching points. This idea of Computer Aided Lesson Planning is basically just an extension of what teachers already do in their everyday lesson preparation, cutting, pasting, adapting, and extending activities and authentic texts from various sources into their own new (but highly derivative) material.