A great way to assess learning, when you can’t perform a formal assessment, is to demonstrate learner improvement via a pre- and post- Likert Scale strategy. You just take the objectives of the course, and have the student self-report their own knowledge in a quick survey. It takes very little time to design (since it’s based off of the course objectives), very little time to participate in (3-7 questions with no wrong answers), and if you have the student fill it out in class, you will have 100% participation.
Ideally, you would be able to perform a formal assessment of the learner’s knowledge. When you are unable to, at the very least you should perform a Likert pre- and post- assessment to demonstrate to the learner their personal development.