Motivation is content specific. Students in various subject areas are likely to rely on different motivators, such as task values, achievement-goal orientations, and perceptions of competence (Bong, 2001, 2002; Buehl & Alexander, 2005). Situational interest, as a motivation construct, can be influenced by cognitive and physical demand in physical activities (Chen & Darst, 2001). The extent to which it is content specific at unit and curriculum levels remains unknown. The purpose of this study was to compare situational interest between a muscular capacity and a flexibility/weight-control unit in an elementary school physical education curriculum. The participants were third-grade students (n = 524) from 27 classes in randomly selected 11 elementary schools. Situational interest and its dimensions (Novelty, Challenge, Attention Demand, Exploration Intention, and Instant Enjoyment) were measured using the Situational Interest Scale (Chen, Darst, & Pangrazi, 1999). Data were collected immediately after the students completed learning each unit. We used MANOVA to compare the difference of the dimensions between the curriculum units and class means as the unit of analysis. The multivariate analysis revealed no statistically significant differences in Situational Interest (F = 2.115, p = .158) and its dimensions: Novelty (F = .330, p =.571), Challenge (F = 1.849, p = .186), Attention Demand (F = .019, p= .892), Exploration Intention (F = .085, p = .773), and Instant Enjoyment (F = .003, p = .953). The findings suggest that the function of situational interest may be generalized across the two physical education units in the elementary school curriculum. Theoretically, the findings suggest that not all motivation constructs are content specific. Situational interest may be one of the motivators that can have motivational impact across content domains. The findings also support the notion that situational interest should be incorporated in physical education curriculum design not only at the task level (Chen & Darst, 2001), but also at the unit and curricular level (Chen, Ennis, Martin, & Sun, 2006; Sun, Chen, & Ennis, 2006).Keyword(s): curriculum, elementary issues, physical education PK-12