This report describes evaluations of two courses which were conducted, primarily through participant observation, in 1981. A general introduction looks at simulation in computer assisted learning (CAL) and at use of simulation CAL in the Open University science faculty. The first study discussed was based largely on a tutor's observations of student interaction with three genetics simulations during a week-long, summer school biology course. The simulations were EV299, a simple model of natural selection; OPERON, a more difficult program; and LNKOVR, which allows students to genetically map an "electronic organism." Evaluation of the second course focused on the CAL experiences of students during a summer school quantum mechanics course that involved use of two simulations: WELLS, which is used to find the eigenfunctions and eigenvalues of particles in potential wells by numerical integration of Schrodinger's equation, and MEASURE2, which allows students to describe what happens to eigenfunctions when various types of measurement are performed on a quantum harmonic oscillator. Study conclusions, a summary discussion, and six recommendations regarding CAL simulation in distance learning are included. (LMM)