The same objects that would be placed in a row in the middle of a note card within ACL 3.4 will be placed along the edge or perimeter within ACL 3.6. Their attention has expanded to include the surface they are placing the objects on, and that surface has outlines that are shapes.
Colouring in ACL 3 is like music in ACL 2. The beat of the music and the shapes to be coloured must be rooted in the human DNA to mesmerise people the way that they do.