Functional fixedness, or thinking about objects only in terms of their functions, is another kind of mental set. An envelope is something to put a letter into rather than a container for sugar when you are having a picnic. Solving the sugar problem requires thinking about envelopes in new and creative ways. Creativity has been measured in various ways: for example, by testing the degree to which people think divergently, exploring ideas freely and generating many solutions, or convergently, following a set of steps which appear to converge on one correct solution to a problem. The more uses they can think of for common obiects such as a house brick the more divergent or creative they are said to be. Creativity can be used in many ways: creative people better than others at rationalizing their actions, and have been observed to cheat more too.