Building a knowledge base is all about categorizing a model representing facts about a topic. Pick a topic - like a person, a place, or a thing - and then build a model of that topic. Use some of the techniques and model-building strategies described in this lesson. An example would be creating an ontology of a living room with furniture, lights, and so on. How does the living room differ from the kitchen? The bathroom? How do you know it's a living room and not a dining room? Use Protégé to build your ontology.