To better describe the previous findings of inconsistency in the relationship between learning time and academic achievement, we tested new models with different shape and pattern to find what might be the optimal describing pattern between the two concepts. Selected from a large-scale international database – the Program for International Student Assessment (PISA) 2015, science learning time and its corresponding achievement was chosen as an empirical illustration. We further tested if culture could moderate this relationship. Using a multilevel model, it was found that (i) there was a quadratic relationship between learning time and science achievement: science achievement rose with an increase in learning time before an optimal point, and fell when the learning time extended beyond that point; (ii) there was a difference between eastern and western leaners on the quadratic relationship, as eastern learners' performance increased and decreased more sharply with the change of time than that of the western counterparts.

为了更好地描述先前在学习时间和学业成绩之间的不一致的发现，我们测试了具有不同形状和样式的新模型，以发现这两个概念之间的最佳描述方式。从大规模的国际数据库（2015年国际学生评估计划（PISA））中选择科学学习时间及其相应的成绩作为经验例证。我们进一步测试了文化是否可以缓解这种关系。使用多层次模型发现：（i）学习时间与科学成就之间存在二次关系：科学成就随着最佳时间点之前学习时间的增加而上升，而当学习时间超过该点时则下降。