An electronic learning aid for teaching arithmetic skills includes a question engine for selecting and communicating to a user a plurality of questions, one question at a time. The aid has a manually operable input device for use by the user to respond to the questions, and the question engine has at least one mode in which the engine ceases accepting a response to a question upon the entry of an incorrect alphanumeric character. The question engine, in response to the entry of an incorrect alphanumeric character, displays a subsequent question and waits for a predetermined period of time after display of the subsequent question before accepting a response to the subsequent question.