This paper explains the design and psychometric quality of a battery of multiple-choice quiz as formative e-assessment for teaching differential equations. It was a preliminary experiment conducted inside a second course of calculus (Mathematical Analysis 2) for about 200 students in Managerial and Electronic Engineering at University of Udine. A survey was also administered to evaluate the appreciation of the students about the quizzes. From the survey, we found out that the quizzes were well chosen, and they discriminated adequately between higher and lower student subject knowledge. Moreover, they helped students to find gaps in their preparation and to keep up with the lessons.