is study.
3. All students in the study attended the same middle school in a single geographic location (New York). The extent to which findings would be different if students attending other schools in the same or in a different geographic location cannot be known on the basis of this study's findings.
4. The study examined for the effects on math performance of only two types of manipulatives (rods and cubes). The outcomes that would have been obtained if other manipulatives had been used cannot be known on the basis of the findings of this study.
6. The period during which math manipulatives were used as part of instruction lasted only ten days. The extent to which findings might have been different if the period of instruction were longer or shorter cannot be known on the basis of the findings of this study.
There were 51 eighth grade students serving as subjects in the study. All students were drawn from a medium-sized middle school in the borough of Manhattan, NYC.
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