Working in groups sounds a great idea - and it is a key tool in a teacher's armoury.
However: it is very time consuming.
You may get one, and only one, chance to talk to any one group of pupils - and you may have only one lesson to do it in. 50 minutes rushes by and you will probably find that you don't have sufficient time to cover the points you feel are important. Individual or group work takes up huge amounts of time.
Our general advice is: don't do it unless this is your second or subsequent visit and you have already made your key points.
Having said that, some people like to involve the class in some sort of activity - after all, listening to someone talk for 30/40 minutes can become a little boring - unless you have the ability to really hold their attention and you respond to questions as you go along. Never bore your audience!
Never do group work unless you have asked the teacher to arrange the groups before you start. Self-selecting groups can be a big mistake, especially at secondary level. The teacher will know who works best with whom and who never to put with whom.
Group work can be very time consuming - don't forget, you need to get your material across and you need to leave time for questions and discussion.
It can work if, after introducing yourself and giving the title of the talk, you ask pupils to work with their neighbour to try to answer some very simple questions. You could tell them that:
"very young children often ask very simple questions which, when you think about them, aren't simple at all."
You could try these questions:
- What is god?
- What does god look like?
- Where did the idea of god come from?
- Further up the secondary school you could add "is god male or female?" That usually generates a very interesting discussion as to why god should have a gender and what the long term results have been of religions referring to god as "he".
Give them two or three minutes then ask for hands-up from those who feel they have some answers.
This is very heavy stuff and it is rare for religious people to give a straight answer, let alone school pupils. It makes the point that the one thing common to religions, belief in one or more gods, turns out to be far more vague than religious people would like you to believe. Faith seems to be belief in the indefinable.