Presents evaluative work based on the computer algebra system (CAS) TREEFROG which enables drill-and-practice examples to be attempted with immediate, and ultimately intelligent, feedback. Contends that by using a suitable repertoire of black and white box CAS, a full range of algebraic skills can be developed. Presents preliminary evidence based on the use of TREEFROG that addresses the specific gap of pencil and paper skills. (Author/ASK)