There is perhaps a happy medium
Reducing class sizes is extremely attractive to parents, although there is little evidence that such a strategy consistently improves attainment.
As the size of a class or teaching group gets smaller it has been suggested that the range of approaches a teacher can employ and the amount of attention each student will achieve will increase. So, intuitively, it seems obvious that reducing the number of pupils in a class will improve the quality of teaching and learning, for example by increasing the amount of high quality feedback or one-to-one attention learners receive
But John Hattie revealed in his book “Visible Learning” that class size doesn’t really matter. Or rather, his research showed that on a list of factors that affect student learning class size mattered the least, which is not quite the same as saying it doesn’t matter.
Reducing class size is very expensive because it means recruiting more teachers. And the teachers you recruit and train have to be good to have an impact. Research suggests that there are less expensive interventions that are actually more effective in raising attainment.(Hattie lists them)
In his book ‘ David and Goliath’, Malcolm Gladwell pointed out that 77% of Americans believe that it makes more sense to use taxpayers money to lower class sizes than to raise teachers’ salaries. Class size is an issue that most parents think they understand. Indeed temptingly small class sizes are used to entice parents into the private sector, where class sizes tend to be smaller. Gladwell pointed out that when the governor of California announced plans to reduce the state’s class size, his popularity doubled within three weeks. The Tennessee’s Project STAR which had inspired the governor to act —was commissioned by the state legislature in the mid-1980s— and it found substantial evidence that reducing class size improved student academic achievement .Its Class Size Reduction (CSR) programme was phased over four years. Its purpose was to decrease the population of K-3 classrooms to no more than 20 students .Other governors then followed suit. However, a state-mandated, four-year evaluation of California’s CSR programme ultimately described its assessment of the programmes relationship to improved academic achievement as “inconclusive” (Bohrnstedt and Strecher, 2002). Eric Hanusheks research on class size reduction also raises doubts over its impact on attainment
Gladwell points out that we have become “obsessed with what is good about small classrooms and oblivious of what can also be good about large classes”. A classroom containing 18–24 students appears to be the ideal number. Anything less and you lose the unique excitement that comes from a critical mass of engaged students.
The Education Endowment Foundation, here, says of class size ‘ overall the evidence does not show particularly large or clear effects, until class size is reduced to under 20 or even below 15.’ It continues: ‘The key issue appears to be whether the reduction is large enough to permit the teacher to change their teaching approach when working with a smaller class and whether, as a result, the pupils change their learning behaviours. If no change occurs then, perhaps unsurprisingly, learning is unlikely to improve. When a change in teaching approach does accompany a class size reduction (which appears hard to achieve until classes are smaller than about 20) then benefits on attainment can be identified’
Surveying studies, Gladwell observes that although really big classes are a problem, there is a happy medium, and smaller classes don’t necessarily lead to better outcomes. This, he explains, is because teachers don’t usually adjust their teaching style to smaller class sizes; instead, they just work less. So, the “disadvantage” of moderately big classes isn’t one after all.
When Gladwell talked with teachers about class size he found there was general agreement that large class sizes can impair learning. However ,he also discovered that teachers believe that the same is true about small class sizes. Teachers agreed that when classes became too small the group dynamics in a class became difficult, and individual students were more easily able to dominate the group and disrupt learning.
Based on this Gladwell suggests that the relationship between class size and achievement is actually not linear (as class size goes down learning goes up), but is best represented by an inverted U curve. As class size is reduced, learning improves until the optimum class size is reached. However if class size drops below the optimum learning declines.
The optimum class size will vary according to the makeup of the class and the various learning needs of students. The optimal class size for a high needs class will be lower than for a class of well-adjusted, independent students. As Gladwell points out in a note in the book, children with special needs do seem to benefit the most from being in a small class.