Group work, observing them, check out how they do their classwork.
Give them class works as well as home works to go do them at their homes.
I assess student learning by their questions, their responses to my questions, their willingness to start work, and their questions to their peers. Also I use quick writes, and summaries, or a verbal sharing time with their neighbor.
Watching them in class and seeing what they do naturally.
I look for clues like eye contact, circling key terms, communicating to other students, quick writes and quick summaries at the closoure of a lession.
In addition to tests, I like to use observation and activities to assess student learning.