A comparative study of computational estimation ability and strategies used in estimation problems.

摘要

his study examines the question: does context affect students' performance when estimating solutions to computational problems? Two aspects of students' performance were examined: (1) does context affect students' ability to estimate solutions to computational problems and (2) does context affect students' choice and use of strategies for making estimates.;Three forms of an assessment--contextual, numerical, and word problems--were developed by the researcher and administered to 236 seventh-grade students. A stratified sample of 60 students was interviewed to determine the strategies used to make estimates.;An ANOVA of scores of the assessments, with estimation ability as dependent variable and format as independent variable, showed that students assessed under the contextual format performed better than students assessed under the numerical and word problems formats in both group assessments (p ;Rounding to whole numbers and arithmetic algorithms were used most often for problems in numerical format and word problems format, respectively. Rounding to tens, rounding to whole numbers, and "nice numbers" were used equally often for problems in contextual format. Rounding to halves and wholes and "other" strategies were used more frequently by students assessed under the contextual format than by students assessed under the numerical (p ;The average number of strategies used per student was not significantly different for the different formats, and no interaction for ability levels and assessment formats was found. Students with higher estimation ability used more strategies and, in particular, used "other" strategies more often than students with lower ability.;Significant correlations were found among students' ability to estimate and (1) students' perceptions of mathematics ability (p ;No gender-related differences were found for estimation ability or for perceptions of mathematics ability. Males rated themselves significantly higher than females in ability to estimate (p