The program thus allows students to concentrate on the essential logical problems underlying the proofs, and it gives them immediate feedback for both correct and incorrect actions. ETPS permits students to work forwards, backwards, or in a combination of these modes, and provides facilities for rearranging proofs, deleting parts of proofs, displaying only those parts of proofs under active consideration, saving incomplete proofs, and printing proofs on paper. The convenient formula editor permits the student to extract needed formulas which occur anywhere in the proof, and build new formulas from them. Descriptions of the rules of inference are available online. When the teacher permits it, the student can obtain hints from ETPS concerning what to try in various situations.
Students can send remarks or questions to the teacher without leaving the program.