In this talk we report on a catalog of modular materials, with interactive learning objects and online assessment, covering a few topics of Precalculus (grade 10-12 ) which we developed at the Mathematical Department of Instituto Superior Tecnico, Technical University of Lisbon. We also report on an experiment of online assessment during this fall semester of first year undergraduate students on these topics. Most of the first year undergraduate students at our Institut encounter in the last decades very strong difficulties at the Calculcus and Algebra courses due mostly to an incomplete preparation in several Precalculus topics. In order to overcome this situation a group of fellow professors of the Mathematical Department decided to develop some topics of Precalculus in a modular, interactive and easy way to exercise and assess. These Precalculus curriculum materials of grade 10-12 are with accordance to national curriculum standard and exposed in three moments: learning, exploring and exercising. Learning facts are considered past knowledge to be remembered and includes an explanatory part and illustrative graphics. Exploring makes use of manipulatives to test the knowledges and assure a more deeply understanding of the subject. Finally, there are series of assessment questions, mostly multiple-choice questions, which are intended both as a learning check for students and as a control check for teachers.