What is the main purpose of common assessments in the PLC model?

The use of common assessments increases the likelihood that students will have access to the same curriculum, acquire the same essential knowledge and skills, take assessments of the same rigor, and have their work judged according to the same criteria.

Why assessment is important and what is it for?

Assessment plays an important role in the process of learning and motivation. The types of assessment tasks that we ask our students to do determine how students will approach the learning task and what study behaviours they will use. ... Well-designed assessment methods provide valuable information about student learning.