This paper reports on the findings of the evaluation of Learning Units (LU), a special type of Learning Object designed to help overcome the difficulties associated with learning Calculus concepts at undergraduate level. An Interactive Platform for Learning Calculus (PIAC) that serves as a container for the LU was created following a specific instructional design, namely, the Teaching Unit Model (TUM), which in turn, rules the platform's design, development and implementation. A general perspective on the development of the platform and its LU is presented, including the results of usability and functionality evaluations, which indicate that the platform and the LU comply with different functionality and usability criteria which are fundamental for their introduction into formal university courses. The platform was utilized in a higher education Calculus course, and its effects on different aspects of the learning process were studied. Two experimental groups and two control groups for a total of 102 students taking the Calculus course participated in the study. Results indicated an overall acceptance of using PIAC in class. Important evidence was obtained on the positive effects of using PIAC, not only influencing academic performance of students, but also in motivational aspects of the learning process. The grades obtained in all of academic activities by the groups using PIAC, compared with the control groups, provide solid evidence to the positive influence of the intervention of the technology under the TUM. (Contains 11 tables and 2 figures.)