Do you ever have those lessons where things didn't go to plan, but went really well nevertheless? Sometimes you have to improvise or adapt to circumstances and no doubt part of being an effective teacher is having the ability, sometimes borne of experience, to adjust a lesson on the spur of the moment.
In Jack C. Richards' excellent book Key Issues in Language Teaching (2015) Chapter 6 is devoted to the theme of increasing the effectiveness of lessons. He begins his chapter with a section on adjusting the plan during the lesson. He describes some of the unplanned decisions teachers have reported making during a lesson - he calls them interactive decisions (from Richards, 1998).
- Dropped activity because of time.
- Added activity to fill out time.
- Added activity to liven up the class.
- Modified activity to increase interest level.
- Changed sequence of activities.
- Elaborated an activity.
- Changed grouping arrangements.
- Changed or dropped activity because of difficulty.
- Dropped activities that didn't seem necessary.
- Added activities to strengthen the lesson.
- Modified activity to change the language focus.
- Added an activity to provide more language work.
Richards goes on to quote a teacher and teacher educator from Brazil, Isabela Villas Boas, who explains how important incidental teaching is. She writes; "Teachers have to be sensitive to unplanned but rich learning opportunities that arise during a class and let go of the lesson plan, even if for a short while, to take advantage of students' interest and motivation."
A good example she mentions is when unplanned but interesting vocabulary comes up. In this case, because of the unplanned context in which the vocab arose it's more likely students will remember it. Your sudden enthusiasm for something spontaneous like this may well communicate itself to the class too. Another example would be when you realise that the class is far less capable of manipulating a language structure or area of vocabulary than you thought, so you feel the need to do some additional practice on the spot. Further common instances of needing to improvise are when behaviour during a task is not right, when technology lets you down or when you suddenly learn your class is curtailed because of a whole school activity.
Now, I would add that this ability to improvise is a a great and subtle skill which depends on a range of factors, among them your cognitive and affective empathy with the class. How well do you judge in real time the level of challenge and interest of the task you are working at? Your formative assessment skills help a lot with this. Experience will also tell you when an improvised activity is worthwhile or just time-wasting as well as how well certain activity types are progressing and when a twist to the lesson is needed. Then there are those occasions when in your planning you forgot to include a really good task, then realise during the lesson you can use it effectively.
Sometimes of course the improvised activity doesn't work out quite as you had hoped, but that's the nature of teaching. It's interactive, subtle, dependent on the class in front of you, your mood on the day and your level of preparedeness. Incidentally, sometimes you can include something in your plan, then make it seem to students as if it were improvised! "Ooh! Now this is interesting! I wasn't going to teach you this, because normally I'd do it with older classes, but I think you're smart enough to get it."
So careful planning of lessons is vital, but I wouldn't be too concerned if you sometimes go hors piste if the returns are worthwhile.
Richards, J.C. (ed) (1998) Teaching in Action: Case Studies from Second language Classrooms, Alexandria, VA: TESOL
Richards, J. C. (2015) Key Issues in language Teaching. Cambridge.