To optimally improve student learning, principals must be visibly participating leaders of teacher learning. This is depicted in Viviane Robinson's aspects of instructional leadership, assigning a large effect size of 0.84 to the role.
Effect size indicates the difference between two groups; one not applying a strategy and the other applying the strategy. The average effect size for a student is 0.4. An effect size greater than 0.4 means the strategy improves learning to an extent relative to the size.
To understand more about Robinson's graphic, select the links below.
Improving teaching & learning
Image courtesy of Viviane Robinson