Brainstorming is a concept generation method in which several designers rapidly generate concepts.  Unlike Collaborative Sketching, communication between designers is less structured.  The objective of brainstorming is to generate a large number of diverse solutions, from which concepts can be chosen for further investigation.


Brainstorming has two basic variables: the number n of designers participating and the time t spent on the brainstorming activity.  Otto and Wood (2001) suggest some constraints on the brainstorming process: (1) generated ideas should not be overly criticized, (2) group members should not consist entirely of domain experts, and (3) hierarchically structured groups should be avoided.

The basis protocol for Brainstorming is as follows:

  1. Designate a facilitator.  The facilitator does not directly contribute to concept generation but encourages others to contribute.
  2. Review the problem.
  3. Generate concepts for a given time t, usually 20-25 minutes.
  4. If ideas have not stagnated, brainstorming can continue if desired.  If ideas have stagnated, stop or use concept generation tools like SCAMPER, etc., to generate more concepts.

Collaborative Sketching


Collaborative Sketching, also known as C-Sketch or 5-1-3 G, is a method for concept generation in which several designers each sketch a design concept then pass their sketch to another designer to modify.  Developed by Shah, collaborative sketching originated as a modification to Method 6-3-5.  A key difference between collaborative sketching and Method 6-3-5 is that designers only work on one design at a time, whereas in Method 6-3-5, designers work on three designs concurrently.


Collaborative sketching has two basic variables: the number n of designers in the loop and the time t allocated for each iteration i.  The number of iterations equals the number of designers.  Therefore, a design team using C-Sketch will produce n designs.  The two constraints in this method are (1) sketching is the only mode of communication between designers and (2) a designer cannot fully erase the sketch of another designer.

The basic protocol for C-Sketch is the following:

  1. The design team reviews the design objectives and chooses a facilitator to keep track of iteration time.
  2. The facilitator begins the first design iteration and each designer sketches a concept to meet the design objectives.  This is the first design iteration.
  3. After t minutes are up, the facilitator instructs the designers to pass their sketch to the left or right.  Designer j passes their sketch to designer j + 1, and designer n passes their sketch to designer 1.
  4. Each designer then adds, subtracts, or otherwise modifies the sketch passed to them for t minutes.  This is the second design iteration.
  5. Steps 3 and 4 are repeated for n – 2 more iterations.