The in-depth analysis is subject of Section 2. In Section 3,
we will elaborate on what we mean by rapid prototyping of
learning applications. We will present two examples that we
realized: micro-blogging for language learning 3.1 and social
bookmarking for authoring learning object annotations
3.2. These two projects allowed us to learn practical lessons
about using Web 2.0 services for prototyping, which we will
discuss in Section 4. We will start by brie
y introducing one
of today's prevalent learning theory, constructivism, which
will provide a context for the subsequent analysis.