1. When faced with a complicated problem, it is often useful to brainstorm several possible solutions first before deciding on which strategy you will apply.
2. Before we began writing, our teacher asked us to brainstorm topics for our compositions.

Brainstorming is often a formal step in problem solving. The goal is to generate potential solutions without immediately evaluating them. Evaluation is carried out as a subsequent step. The word “ brainstorm” is a verb, but its –ing form, brainstorming , is often used as a noun (as in the first sentence in this paragraph).