Computational science includes the use of computer-based modeling and simulation to define and test theories about scientific phenomena. The challenge for educators is to develop techniques for implementing computational science in the classroom. This paper reviews some previous work on the use of simulation alone (without modeling), modeling alone (without simulation), and computer-based modeling and simulation. In addition, it describes Emile, an environment which offers software-realized scaffolding to support student modeling activities. Four figures depict a physics explorer simulation of gravity; a student's simulation created in Emile; and Emile text program components. (Contains 23 references.) (AEF)