[susan53]

I've never taught engineers (and it depends on what type of engineers they are), but I'll try and give some general examples which might be applicable to an intermediate group.

In a controlled practice activity, what the S has to produce (say) is 100% predictable and 100% confined to the target language (what the teacher wants to practice) - there's no room for choice. So for example : let's say the teacher wants to practice numbers. She gives the Ss a picture of a bridge with the length etc marked and asks questions : How long is the bridge? How wide is the bridge? How many cables are there? etc The Ss answer 15,000 metres /30 metres / 250 etc. They are only saying the numbers (the target language) and nothing else - there's nothing else to say. So : 100% confined to the TL and 100% predictable.

This can be made more communicative (but still 100% controlled) by dividing the info into two tables an pairing the students. Student A has ...

How long is the bridge? 15,000 metres
How wide is the bridge? ------------------
How many cables are there? 250
How many pylons are there? --------------
etc

Student B has ...

How long is the bridge? -----------
How wide is the bridge? 30m
How many cables are there? --------
How many pylons are there? 600
etc

In pairs the ss ask and answer the questions. Obviously they have to ask about the info they don't have, listen to their partner's answer and write it down. Notice that here they don't have to think of the questions - they're given. So although they have to say the questions, they don't have to formulate them. The only language they have to focus on formulating is the numbers.

In a freer practice activity the language would still bring up the target language in continuation, but the students would have to incorporate it with other language and exactly what they said would not be 100% predictable. Eg :

Student A has info on the Vasco da Gama bridge, expressed as concisely as possible - eg : Length = 16,200m. Student B has parallel info on the Golden Gate Bridge. They are asked to decide which bridge is the longest/widest, has the most cables etc. Now, to do this the students must use the numbers (the target language), but they'll need to surround them with other language. But exactly what they say is up to them. So : they could ask questions : How long is the V da G bridge? / It's 16,200 metres but they could equally well choose to say : My bridge is 16,200 metres. What about yours?

Obviously, the CP activities are much easier than the FP activities. That's why it's important to use them at the beginning of the lesson, after the T has modelled and explained the target language, but before the students are asked to use the TL in FP.

Even with CP there can be gradations of difficulty. So - the easiest CP activity is simply repetition. Here the T might hold up a flashcard with a number, say it and ask the Ss to repeat it. The activity with the labelled picture of a bridge and the teacher questioning might come next - the students now have to formulate the nos. for themselves, but that's all. Then the first pairwork activity. Now the students not only have to formulate the numbers which they say, but also listen and understand their partner's replies in order to write the numbers down. And the most difficult of all is the FP activity I described, where the students have to understand what their partner says, and think of what they themselves want to sayin reply and how to say it, all in real time.

So the lesson moves gradually through simple to more complex activities, and as the Ss become more confident with the numbers they are asked to use them in increasingly complex activities - activities which, if used at the beginning of the lesson without this gradual preparation, would be far too difficult.

Hope that helps. If you'd like the titles of a couple of books that explain things in more detail and would give you more examples, send me a PM.