The ubiquitous "Are there any questions?" at the end of a lecture is so routinely ineffective that it has come to mean "That's all for today." During a lecture it doesn't work very much better. There are some good reasons for this:

1. Students may be too busy writing notes on what has just been said to formulate a question.
2. Dictation or fast presentation requiring full note-taking does not encourage thinking of any kind, let alone questioning.
3. Only brief silences are normally tolerated during lectures, and sensible questions may take a few moments to formulate.
4. An unspoken ground rule may be operating to the effect that getting through to the end of the lecture quickly is the primary goal. Questions may result in the teacher having to rush later on or even miss out the last section of the lecture altogether. This may cause more problems to students than the failure to have their questions answered, and so they collude with the teacher to avoid interrupting the presentation.
5. Even when a student has managed to formulate a question, she may need an opportunity to "try it out" (to check that it doesn't seem silly) before she is prepared to ask it in public.
6. Students who ask questions run the risk of being considered stupid, attention seekers or creeps.

As a result it can be unusual for invitations to ask questions to be taken up. The larger, more formal and impersonal the setting, the less likely it is that student will ask questions. To get round these problems the teacher may need to:

1. Give students time in which to formulate questions;
2. Give students the chance to check out that their questions are not silly before asking them in public;
3. Ask everyone to formulate questions so as to avoid the stigma attached to the questioner.

You could say: "Now I'd like to give you the chance to ask me questions about what I have just explained. You have half a minute in which to write down the questions you'd really like to have answered, or a query you would like to raise. OK, I'm going to go along the third row back asking each person in turn to read out their question. So... what is your question?"

Or, "Could you please turn to your neighbour and raise any questions you have at this stage. Try and answer each other's questions. If you can't, write the question down. In two minutes I am going to ask a couple of pairs what their outstanding questions are."

Extract printed with permission from 53 Interesting Things to Do in Your Lectures, 4th Ed., 1995 by Graham Gibbs, Sue Habeshaw and Trevor Habeshaw, ISBN 0 947885 03 X TES Ltd., Bristol UK, www.53books.co.uk.