This is kind of a neat process: the fishbowl --
Divide the class in two and have one half sit around desks pushed together in the center of the room; the other half sits around the outer perimeter of the room. Leave an empty chair at one end of the center group.
Pose your question (make it a VERY open-ended question!) and let the group in the center run with it. If anyone from the outer group is burning with a question of his/her own, that's what the empty chair is for -- that that person can only ask a question, no voicing opinions or giving answers.
About halfway through the time, have the groups switch, and do it again with the groups reversed.
Here's an example of an open-ended question: "After reading Exodus, what do you think 'Law' is?"
Another technique is "discussion tag".
Divide the class into 5 or 6 equal groups. Give each group one aspect of the discussion topic. Then give them a day to prepare. The next day let each group draw a straw for the person to represent the group in the "middle". Then as the discussion progresses, members from the group can swap members, but a member can only go in once. You can also use an alarm clock to set a discussion time and let the whole group swap out.
Thanks, but too bad i only have one day to lead the discussion and the room is too confined that it is not possible to move around. Any other suggestions? What kind of small activities could i do?