But achievement tests also have limitations beyond those attributable to hasty, inexpert construction or improper use. In the first place, they are limited to measuring a person’s command of the knowledge that can be expressed in verbal or symbolic terms. This is a very large area of knowledge, and command of it constitutes a very important human achievement; but it does not include all knowledge, and it does not represent the whole of human achievement. There is, for example, the unverbalized knowledge obtained by direct perceptions of objects, events, feelings, relationships, etc. There are also physical skills and behavioral skills, such as leadership and friendship, that are not highly dependent on command of verbal knowledge. A paper and pencil test of achievement can measure what a person knows about these achievements but not necessarily how effectively he uses them in practice.