Final answer:
A learning activity coded at a 3 involves students refining models or representations of phenomena or systems, indicating higher-order cognitive work and deeper understanding.
Step-by-step explanation:
When a learning activity is coded at a 3 in terms of knowledge construction, this indicates that the learning activity involves the ability of the student to refine representations and models of natural or man-made phenomena and systems within a particular domain.
It suggests a higher level of cognitive engagement where students are not just understanding or applying concepts but are improving and enhancing existing models and representations to better understand and explain the phenomena or systems they are studying.