An ELT Glossary : Drills

Behaviourist theory was applied to second language learning in the 1930s, when the Audiolingual Method was developed. It posited that learning was a matter of habit formation - and that habits were formed by constant repetition of the same action which, if it received positive feedback (which might be anything from another person's approval to "realising it worked"), would gradually become automatic.

To allow learners constantly to produce the same structures, thus forming this type of automatism, audiolingualism used  various types of drills/drilling techniques, all based on the idea of the repetition of the same target language items again and again, and involving a stimulus (provided by the teacher or recorded materials) and response (provided by the learner) and feedback (provided by the teacher). For example :

Repetition drills : these were based on a model sentence (the stimulus) - eg I go to the supermarket every Saturday - which the learners would first repeat chorally (the response). The teacher would then evaluate the response (the reinforcement) positively or negatively. After that, individual learners might be asked to repeat the same sentence, again receiving positive or negative feedback.

Substitution drills:  the teacher would start with a model sentence, as in the repetition drill above. After the repetition stage however, the drill would continue. The teacher would provide a stimulus - another word such as library - and the student would respond by substituting it in the model sentence. The teacher's positive or negative evaluation would again provide the reinforcement. For example :

T : OK, everyone - listen and repeat : I went to the supermarket on Saturday  (stimulus)

Ss: I went to the supermarket on Saturday  (response)
T : Lovely (positive reinforcement) - Jean, again  : I went to the supermarket on Saturday. (stimulus)  
J : I went to the supermarket on Saturday. (response)
T   Good.. ...   (positive reinforcement)
T : OK - Ayeesha - library. (stimulus)
A : I went to the library /laɪbə'reriː/ on Saturday. (response)
T : Mmm.... (negative reinforcement) Listen to the pronunciation /'laɪbrəriː/(stimulus)
A : /'laɪbrəriː/ (response)
T : Much better (positive reinforcement) 

Transformation drills : the teacher would again provide the stimulus - I go to the supermarket every Saturday, but the student would have to respond by transforming it into another structure - for example, the negative : I don't go to the supermarket every Saturday.

Chain Drills : The T. starts the drill by saying a sentence containing the target language - eg fot expressions with make and do as delexicalised verbs  : On Saturday I did the washing. The next learner repeats it (changing it into the third person) and adding another sentence : On Saturday Sue did the washing and I made the beds. The third student continues : On Saturday Sue did the washing, Roberto made the beds, and I did my homework - and so on. This means that by the time you get to say the tenth student you have a chain of activities like : On Saturday Sue did the washing, Juan made the beds,  Maria did her homework, Yoko did the washing up, Paolo made a cake, Kurt made a mess in the kitchen, Kateryna made a phone call, Francoise made an appointment with the dentist, Evelina did the cleaning and I did nothing!
If the expressions are on the board, the T. can either indicate which one the learners should use, or let them choose. The activity works best with medium sized groups. With more than about ten students it can get too difficult to remember, and with small groups there's not much challenge - though you can always go round the group twice.
This is also a great activity for getting students to learn each others names - either at the beginning of the course or if new students join half way through. You can incorporate it into a lesson with a structural or lexical aim, and achieve two objectives at the same time - practice of the target language and constant repetition of everyone's name.

Further Reading

Richards and Rodgers, Approaches and Methods in Language Teaching, Cambridge