Experimental methods play an important role in computer science and should be a part of the introductory computer science curriculum. Measuring program performance, testing experimental hypotheses are areas where traditional scientific methodology may be used. Scheme and J systems provide facilities for measurements of memory space and execution time of programs. As an example of a simple experiment which might be performed by introductory students, consider the problem of estimating the execution time of the recursive fibonacci function discussed in Section 2.3. In Section 2.4.1, a J version of this experiment is described. The Scheme description of this experiment is similar.