When you sketch in a group, remember:
Have a goal. Before sketching, establish goals for the activity. Figure out what aspect of the product to model.
Start with a scenario. In addition to a goal, it’s useful to describe a person using the product—how they’re using it, what they want to get out of it, and what their expectations are. By sketching toward a scenario, you establish some reasonable constraints to define the immediate exercise.
Set a time limit. Don’t let people draw for more than fifteen minutes. My sketching sessions usually cap the drawing at ten minutes. Like the scenario, this constraint prevents meandering, getting participants to focus on solving the problem.
Discuss the ideas. The value of sketches is in their speed. Get feedback on the ideas in the sketches before making any final decisions.
Extract the good ideas. Don’t assume you’ll remember the conclusions about the sketching session from the sketches alone. Make a list of what worked and what didn’t.
Sketch again. The cost of iteration is low. Use as many iterations of sketches, with increasing clarity and fidelity, as you need to feel confident about the idea