This study was designed to: (1) outline briefly the meaning and importance of the family of concepts stemming from the ideas of estimation, approximation, checking, and precision; (2) survey the present place of such concepts in the curriculum; and (3) relate the teaching and learning of these concepts to the availability of the calculator as an emerging tool for reducing computational labor. Relevant literature was extensively surveyed: the meanings of the terms were analyzed; their role in the curriculum was traced; and the use of the hand-held calculator was addressed. The following section discusses the literature under the headings of meaning, rationale, research, the curriculum, and teacher strategies. The present place of these concepts in the Ontario school mathematics curriculum was analyzed using surveys of mathematics coordinators and comparisons of textbooks and other documents. Results of the questionnaire survey and document analyses are found in the next section, followed by a brief summary. A bibliography is included, as well as documents related to the survey. (MNS)