Our aim is to improve the quality of educational software by providing some general principles and guidelines for ease of use. Although the Guide is intended mainly for developers of educational software and websites, it should also help users teachers and students and adopters to evaluate educational software and to give feedback to the software developers. Ease of use can be split into three aspects: usability can people use the software effectively and efficiently to perform a task?, usefulness does it improve teaching and learning? and desirability do people enjoy using it?. This guide is primarily about usability. Designing and assessing the usefulness of educational systems is a complex topic, beyond the scope of a short report. Desirability depends on usability the user will not enjoy a system they can’t use but it also involves issues such as motivation, fashion, marketing, and peer pressure. Good software is all of these things, and whilst the guidelines presented here focus on usability, they assist the wider issues as well.