Class size & the concept of 'Intervention Time'

I have heard many times that reduced class size is not a factor in learning or that it has minimal effect. Reduced class sizes is not the panacea to improved student learning but it is a handy tool when used correctly. To have an early intervention strategy there must be adequate class time for intervention.

If you have a high performing class of motivated students (with 3 levels between the top and bottom performing students), class sizes of around thirty in year ten can be managed. You would need to use a fair amount of skill to keep them motivated as after instruction and settling time (say 30 mins per class, two blocks of instruction, h/w and pack up) it would be hard to get to every student every class to identify issues, correct them (say 1 minute of intervention time per student per class) and maintain their learning inertia. You would more reliant on picking up issues during the homework, quiz, revision, assessment and corrections teaching cycle and complete more marking out of class.

In a mid performing class (with four levels between the top and bottom performing students) with around 20 students and 20 minutes of instruction and settling time you could get to each student twice (eg. average of 2 mins of intervention time per lesson). This seems feasible.

If you have a low performing student group in mathematics (with five levels between the top and bottom performing students), I would say that a class of 30 is lunacy (there are usually valid and disparate reasons why students are this far behind) and would send the best teachers barmy. Under normal circumstances in these types of classes there are not enough corners in the room to separate disruptive students. Each student in a class of that type requires constant attention to fully enjoy and appreciate mathematics. For example in my class, one student required behavioural attention once every 3 minutes (I timed him), each time requiring further attention to settle him. In a class of thirty that would make teaching nigh near impossible. For a class of this type it is preferable to have intervention time around 3-4 minutes per student, limiting class sizes to 13-16 students. This size of class would also promote more collaborative work, especially if other teachers are willing to assist during their DOTT or if a T/A is available.

In practice each student does not need (or get) an individual minute of your time and is normally able to do their work without individual intervention through the teacher identifying classwide issues and modifying instructional techniques (eg. more modelling), by using peer assistance, having effective instructional notes, by increasing participation in after class discussion or by bringing groups of students back to the board. What the intervention time model does is provide a benchmark of performance and can help identify structural issues vs teaching issues with classes that are clearly not working.

Using a model of this nature we could measure the learning capacity of student groups (by creating class sizes and monitoring teaching/intervention/disruption time) and the approximate class sizes required to teach them optimally. This has the potential to greatly assist in designing and justifying appropriate class sizes for our students.