As we saw in the theory bit, silent brainstorming can create a bigger set of ideas that are richer in differences.
To do this, simply give to people again about 15 minutes to come up with around 10 ideas all by themselves. People aren't allowed to talk to each other and have to work in silence.
Similar settings consist of sending people for a walk and having to come back and having to come back with a certain number of ideas.
When we do silent brainstorming I either have some music that I play for the group or I ask before people to come with their headphones so that they can listen to some music if they feel uncomfortable in the silence.
Basics of Ideation for Innovation (Alpha version)
A future course teaching ideation theory and methods.