Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Brainstorm Rule: Go for Quantity

The goal of a Brainstorm [ For more on 'Brainstorm' go here: http://www.braingle.com/mind/84.html ] is to come up with many different possible solutions to a problem. Be prolific! Don't dwell on any particular thought unless you are building on it [ For more on 'building on it' go here: http://www.braingle.com/mind/107.html ]. There will be plenty of time to think about the details of each idea at a later date.

The moderator should try to maintain the energy and pace of the meeting by keeping people on track and forcing them to go on to the next idea. If someone is going into a long-winded explanation of something, the moderator should interrupt them and ask for a one-sentence summary.

Having a quota for the number of ideas you want to produce is a good motivator for the group. Try for at least 100 ideas in a half-hour brainstorm.
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For more mind exercises: http://www.braingle.com/mind/