This paper describes our bench-scale student experiment with a continuous stirred tank reactor (CSTR). The conditions under which the CSTR approaches ideal mixing behavior are investigated using CaCl[subscript 2(aq)] as a tracer. The data are derived from transient solution conductivity measurements of the vessel effluent. Adjustable parameters include feed and agitation rates, and liquid volume. Students observe the unexpected result that reasonable mixing can occur in the absence of agitation solely due to the feed stream entering the reactor fluid.