ACER’s learning progressions are concerned with improvement in broad areas of learning. This improvement is essentially conceptualised as an increasing amount of a construct, eg proficiency in reading or mathematics. The quantitative representation of this increase is a continuous numerical scale. In ACER’s view, the numerical scale is a central and necessary feature of a learning progression.

Within one of ACER’s learning progressions, the numerical scale represents a long vertical range of improvement in the learning area. This long vertical range is divided into an arbitrary but convenient number of levels, typically no more than fourteen. The numerical scale underpins a structure of four layers of qualitative descriptions/illustrations of improvement in the learning area:

• the Domain layer
• the Levels layer
• the Strands layer
• the Illustrations layer.