PPP, in case you don't know, stands for Presentation Practice Production. In language classrooms it's the approach adopted by most teachers when they introduce a new grammatical structure or vocabulary topic. The idea is broadly that you present the structure, give students a chance to practise it within narrow parameters, then finally an opportunity to use the structure in a less controlled context. This approach fits well with the skill acquisition view of second language learning and is akin to the way you might teach other skills in life, e.g. learning how to do a side-step in rugby or play a simple piece of music on the piano.
But PPP can come in different forms and may mean different things to different teachers. Let me offer three different ways of applying it.
1. Deductive approach
In this clearest and simplest approach you would present a new structure on the board with examples, e.g. you might explain and show how the comparative of adjectives functions. This is explicit grammar teaching in its purest form and you could enhance the process with translations, using underlining, highlighting or colour to make the key elements clearer to students. Students might then copy down the notes before moving on to some structured practice. This might be in the form of a cloze exercise, a matching task, a spot-the-error task or similar. Translation into English could be involved along with some tightly structured question and answer or other oral interaction. Once you think the class has mastered the structure you then move on, probably in a subsequent lesson, to some production whereby students get the chance to use comparatives in a less tightly controlled fashion. This could involve an information gap task, general conversation questions featuring comparatives or a written task comparing two people.
2. Inductive approach (1)
This differs somewhat from the above in as far as you do not explain the structure from the very start. In this case you would present a limited number of examples of the structure in a meaningful context, e.g. for comparative of adjectives showing three stick figures of different heights, body shapes and IQ (controversial?) and proceed to describe the differences between the three characters. Fred is taller then John, John is smarter than David etc. At some point in the teaching sequence you would then ask students to notice what is going on, what patterns they can see or hear.
At this point you could then present the structure as above in Section 1 in order to make sure all students have understood. You could call this "inductive-lite" since you have not given a great deal of time for students to pick up the structure. Once you have presented the structure, you could then continue as in Section 1.
3. Inductive approach (2)
This has been described in a recent Gianfranco Conti blog here. In this case, you make sure that students hear and read many, many examples of the structure in context. You avoid any explicit grammar explanation for a long time, allowing plenty of time for the structure to become embedded in students' memories. Indeed, you may choose to avoid any explanation at all, if you think students have mastered the structure for themselves. In this approach, which would be favoured by proponents of the comprehension hypothesis (language is acquired by understanding messages), the emphasis is on meaning, but with much repetition of the target structure.
After a lengthy period of assimilation you would then proceed to do some structured practice examples and freer production as described above. In a sense this third approach is barely PPP at all, especially if you omit the explanation phase.
Which of the above three approaches is best? Research does not help us a great deal since no study has convincingly compared in controlled conditions the effectiveness of each. My own preference was generally for (2) but I varied how I taught grammar depending on the class and the structure being taught.
For example, with the subjunctive in A-level classes I chose approach (1), giving quite detailed handouts summarising the formation and use of the subjunctive, before proceeding to structured practice and freer production. Why? Because the range of forms and uses is too wide to teach by drip-feeding and older students who have opted for the subject can handle detailed explanations better.
On the other hand, when introducing a new tense with younger pupils I would usually use (2), often with pictures to support the presentation phase. I felt more comfortable letting students figure out the patterns for themselves, sensing that they might retain them better if they had noticed the pattern themselves without prompting. In addition, the challenge of working something out independently should inherently be more engaging.
With other trickier grammatical structures, e.g. the use of the relatives ce qui and ce que I felt that explanation was more likely to lead to confusion with some intermediate students and felt it was better to let nature take its course, just letting students see and hear them in context. With some classes I would not have taught that structure at all, of course. You have to pick and choose your grammar carefully with lower attaining pupils.
All of this presupposes that we can "teach" grammar at all - some scholars and teachers claim we cannot and that students acquire grammar at their own rate and in their own order. I cannot possibly say for sure, but because of the way I was taught and through my reading, I remain of the opinion that practising structures, as long as you don't do it excessively, is very useful and can, in a school setting, lead to effective acquisition. If I were to hazard a guess at the amount of time I spent focused on grammar I would say that with advanced level students it was less than 10%, and with younger students no more than 30%. And within that 30% the large majority of the practice would have been based on meaningful (if not "compelling") target language.
We discuss these issues in more detail in The Language Teacher Toolkit.