对大量研究班级规模效应的meta分析表明，班级中学生越多，学生成绩水平越低(Glass and Smith, 1978, 1979)。其他重要变量也是负面影响班级规模,如在课堂上教育过程的质量(教师做什么),物理学习环境的质量,在多大程度上学生的态度是积极的,他们表现出的行为有利于学习的程度(史密斯和玻璃,1979)。这些负面的班级规模效应对较年轻的学生影响最大，对18岁或18岁以上的学生影响最小(同上)，但这种效应在高等教育中仍然相当显著。她在英国一所理工学院发现，“一个50-60分的模块得A的几率不到一个20分以下模块的一半。”大班授课不仅会对学生的表现产生负面影响，还会对学生参与的质量产生负面影响:学生更有可能在大班授课时采用表面教学法(Lucas et al.， 1996)，因此他们只会试图记忆，而不是试图理解。独立学习时间在很大程度上反映了课堂接触时间:如果教学越少，学生学习越多;如果教学越多，学生学习越少，无论教学时间与学习时间的比例如何，独立学习时间所占的总时间与独立学习时间所占的总时间相同(Vos, 1991)。然而，一些教学系统使用课堂接触的方式比其他方法更有效地产生有效的独立学习时间。Gardiner(1997)对一些研究数据的回顾发现，在美国大学，平均每一个小时的课下学习时间只有0.7小时。相比之下，牛津大学(University of Oxford)每小时的辅导课平均产生11个小时的独立学习时间。
Meta-analysis of large numbers of studies of class-size effects has shown that the more students there are in a class, the lower the level of student achievement (Glass and Smith, 1978, 1979). Other important variables are also negatively affected by class size, such as the quality of the educational process in class (what teachers do), the quality of the physical learning environment, the extent to which student attitudes are positive and the extent of them exhibiting behaviour conducive to learning (Smith and Glass, 1979). These negative class-size effects are greatest for younger students and smallest for students 18 or over (ibid.), but the effects are still quite substantial in higher education. Lindsay and found in an English polytechnic that “the probability of gaining an ‘A’ grade is less than half in a module enrolling 50-60 than it is in a module enrolling less than 20”. Large classes have negative effects not only on performance but also on the quality of student engagement: students are more likely to adopt a surface approach in a large class (Lucas et al., 1996) and so to only try to memorise rather than attempt to understand.Independent study hours, to a large extent, reflect class contact hours: if there is less teaching then students study more and if there is more teaching students study less, making up total hours to similar totals regardless of the ratio of teaching to study hours (Vos, 1991). However, some pedagogic systems use class contact in ways that are very much more effective than others at generating effective independent study hours. A review of data from a number of studies by Gardiner (1997) found an average of only 0.7 hours of out-of-class studying for each hour in class, in US colleges. I n contrast each hour of the University of Oxford’s tutorials generate on average 11 hours of independent study.