This activity is an example of where I would envisage teaching the same material, slightly differently, with an HL only or HL/SL level 5+ class than with a purely SL or SL Low level 5 and below classes. See Focus on correlation and regression for very good conceptual overviews, and using the GDC to calculate, Pearsons. This activity builds on Covariance to provide a deeper understanding (as preparation for the HL sums...