Expansions in terms ofL2integrable functions, such as Slater or Gaussian orbitals, or Hermite functions, are usually employed to describe bound states of atomic and molecular systems. A less familiar property of these expansions is that they can accurately reproduce continuum wave functions in selected regions of configuration space, yielding a procedure that is widely used in the calculation of probabilities of predissociation and ionization, as well as of unimolecular and bimolecular reactions. In the present work it is argued that the essentials of this procedure can be introduced with a modicum of theory through an extremely simple example, which lends itself to further numerical experimentation.