A teaching aid comprises a card that is narrower than a page of a textbook, and which contains basic facts, principles, relationships, or the like which are being taught in a particular section of the textbook. A teaching method includes having the student maintain the card adjacent to a page on which questions and/or problems are presented and referring to the card as necessary to answer the questions or solve the problems being presented. The student need not transfer his or her attention from the problem or question to a task of locating the facts, principles, relationships or the like pertinent to the questions or problems being solved, which information may be located in other sections of the textbook.