Assessment must be open-source. When we ask our students to pay a publisher to get their homework graded, we are not only asking them to pay for points—we are also outsourcing our core mission. Furthermore, the most engaged students will want to dig into the guts of the assessment platform, necessitating that our students can "open the hood" and look inside the assessment platform. For more on the underlying philosophy, see An Open Perspective on Interactive Textbooks.
The Calculus Knowledge Assessment is a bank of multiple-choice calculus questions openly licensed (CC-BY-SA) with the exception of p12, p05, p06 which are from GoodQuestions and therefore need to have their license status verified.
With its goal of being a large bank of questions, the CKA bank is designed so that the easiest way for students to memorize the answers is simply to understand the underlying concepts.
The Math Education Forum at Ohio State is currently drafting a paper detailing the CKA, measured learning gains in calculus, etc. If you are interested in collaborating (either by contributing questions, providing expert feedback, or working on the data), please contact Jim Fowler.