These prototypes can be used to evaluate research hypotheses quickly.
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 briey introducing one of today's prevalent learning theory, constructivism, which will provide a context for the subsequent analysis.