Making Use of effect size to focus on students’ learning gains.
Based on the work of John Hattie, I would like to suggest that we at Praslin Secondary School make use of effect size to measure the learning growth of the students.

Strategy
Administer a test (a pretest) relating to the curricula to your class in term one.  Mark and record the results in excel.  Administer the same test or post-test of the same variances in term two.  Mark and record the results. For the pretest it does not matter whether the students have covered the objectives or not. It will be a way to discover what they know about the topic they will be taught. Once they objectives have been taught the students are given the post test.
Use the data from the two tests (pretest and post-test) to calculate the effect size, thus helping to understand the impact of teaching over the period. The difference between the average marks is the measure of the effect size.

Use the following formula to calculate the effect size:
Effect size = average (post-test) – average (pretest) divided by
                    Spread (average standard deviation)
This would be the class average effect size.

According to John Hattie, international trends lead to an estimate of an effect size of 0.4 for a year’s input of schooling. The average effect size across all students is 0.40 and an effect greater than that is seen as doing good learning gain.

Individual Effect size
The effect size of individual student can be calculated by means of the following formula:
Effect size =   Individual score (post-test) – Individual score (pretest) divided by
              Average standard deviation for whole class

The information vis-à-vis the students’ progress be communicated to them and their parents, at the same time taking care to avoid students becoming complacent.  The teachers would use the data inquisitively in pertinence to the student’s different types of gains and look for triangulation about the reasons they obtain, and propose strategies to help the students improve.

For each student the difference between their pre-test and post-test scores is a measure of how much he or she has learned. Geoff Petty in his book Evidence Based Teaching, says that a teaching method with an effect size of 0.5 gives one-grade leap and one of 1.0 gives two grade leap in GCSE.

According to Hattie, using effect size invites teachers to think about using assessment to help to estimate progress, and to re-frame instructions to better tailor learning for individual or groups of students. It instigates teachers to ponder on the reasons as to why some students have progressed, and others not – as a consequence of their teaching.