Assignments and activities used to measure our students' progress overtime. They allow us and students to measure their progress overtime. There are two kinds of assessment: formative and summative.
Check out these formative assessment tools. We often use the term low stakes to define formative assessment, but a series of formative assessments can ensure that students are learning material. These tools should be used weekly to check understanding.
This article gives a variety of formative and summative assessment options, and it explains the role these kinds of assessments will have in an online course. These assessments can differ by discipline, but keep in mind that being innovative may require us to think outside of our discipline box.