Brainstorming is sharing ideas about a theme: put several people in a room, ask them to think out loud about a subject, and capture the results. In Spanish it’s called “lluvia de ideas” or an idea shower; I think it’s a better image.

To brainstorm effectively, you will need a team of colleagues/friends/perfect strangers, a skillful moderator to animate the session, and a quite and comfortable place. You’ll also need to ensure that everyone abides by a few simple rules: shoot for quantity, not quality, of ideas; rule out all sorts of criticism; encourage ridiculous/dumb/wild ideas; capture everything; encourage the use of one idea to generate others (build on ideas); and don’t stay too long on any specific idea.

Tom Kelley provides further tips: start with an open-ended question but a clear definition of the problem, number the ideas to motivate the participants (e.g. shoot for 100 ideas per hour), and use Post-its or other props to show progresses and facilitate your future categorizing.

If you can, try to assemble as heterogeneous a team as possible. Have a complete novice and a subject matter expert. Have a highly creative fellow and a highly analytical one. Get someone that really sticks to your organizations’s lines and a pure iconoclast.

You might want to jumpstart the session with a warm up, such as asking the group to name ten types of trees. Then ask everyone to contribute ideas and capture them. Don’t satisfice by stopping at the first idea that sounds about right; on the contrary, keep drilling for more ideas, irrespective of their quality.

Avoid all criticisms. That’s negative and positive criticisms. As a moderator, don’t offer encouragements when you hear ideas: “this is good” or “I like that” might motivate whoever receives it but it will demotivate everybody else that didn’t receive praises when they spoke. When someone contributes an idea, repeat it as you write it down, just write it down, or ask for clarification if needed.Brainstorming are truly successful when you make the group builds on each other’s ideas. Tim Hurson describes this dynamic by breaking a brainstorming session in three thirds. In the first third, everyone contributes ideas that are somewhat general: given more time, everybody in the room would probably have thought about them. In the second third, people start building on each other’s ideas. But the final part is when these new ideas really shape up. Even if there is value in this dynamic, don’t spend too much time on any single idea: it is an idea shower, not an idea bath. You’ll have time in other sessions to drill in depth.

When I joined academia, I asked Robert Patten, one of my mentors at Rice, for tips to make me a better teacher. One of the two ideas he gave me was the following: “around half of the term or a bit later, your students that will say that they can handle anymore. You’ll see them tired, they’ll tell you that they have too much work in their other classes, they’ll say that they don’t understand the material, etc. This is precisely when you want to push on because it is when they have to outgrow themselves.”

It’s the same with brainstorming sessions: it is when the group thinks that it can’t contribute anymore that the good stuff happens: you have already flushed out all the obvious and not-so-obvious ideas. Now they really have to build on the ideas of others; now you’re about to hit the truly innovative stuff. Remember that they will want to satisfice, so push them onward!