A tagger for teaching purposes

This paper describes a software system intended to help students learn about the process oftagging, the assignment of part-of-speech labels, which is basic to computational linguistics. Itdoes this by (a) making it transparent why words have been analysed in a particular way, and(b) making it straightforward to add items to the system’s lexicon and improve itsgrammatical coverage. An unforeseen and welcome side-effect is that users are led to reflecton various properties of English grammar.