The document discusses principles of user-centered design for developing products. It states that the requirements of the intended users should be determined by discussing users' needs and analyzing existing systems to identify problems. In developing a product, a variety of representations or models should be created and tested until a suitable design is produced. These models can be used to test ideas and make predictions about how users will interact with the product. The document advises that when developing a learning package, the requirements should first be determined by examining other packages, and analyzing the needs and abilities of the intended users/learners.