This paper describes the educational tool VAST. We designed VAST to be used in compiler and language processing courses. The current version allows generating and visualizing syntax trees and their construction process. The main advantages of VAST follow: it is designed to be as independent from the parser generator as possible, it allows students to visualize the behaviour of parsers they develop, and it has an interface designed to easily handle huge syntax trees. We describe different ways of using VAST in educational settings as well as a usability evaluation.