I We discussed the implications and limitations of Pygmalion in the classroom and other investigations on teacher expectancy effects, and emphasized the importance of naturalistic studies. II We investigated the inflnence of prior experiences with an older sibling upon teacher expectations and student achievement by younger siblings. We identified 124 pairs of siblings who were taught by the same teacher (experimental group) and 488 pairs of siblings who were taught by different teachers (control group). We compaired the grade point average data of each sibling and found that the discrepancies of the grade point average between experimental siblings were smaller than that between control ones. It is interpreted that teacher expectations formed through prior experiences with an older sibling produced this difference
