Progress tests are tests given during a course to check how well the items/subskills taught up to that point have been assimilated and retained. They have a formative purpose - ie they help the teacher and learners decide how successful the learning has been to that point, what needs recycling and consolidation, whether different learning strategies need to be introduced and used etc etc.
For example, a text book with twenty units might provide a test after every five units which focuses on the language items/subskills that the learners have met in those units.
