Jasper - a Javascript Proof Editor

This paper discusses the construction and use of Javascript Gadgets for inclusion in web-based teaching materials. The term gadget is being used loosely to describe a tool that animates or allows interaction with some part of the teaching material that is being presented. In the context of HTML-based teaching material, the programming language Javascript is ideal for producing small client-side interactive gadgets that can be included inline with the teaching material. Jasper is a gadget which supports the user in applying equational reasoning. A series of steps using equational reasoning produces a proof and so the tool qualifies to be called a proof editor. Equational reasoning is loosely described as substituting "equals for equals" and so its rules are presented as equations. Jasper can be used in a wide variety of equational reasoning situations. At its simplest it can be used to teach or remind students about 'school' algebra (using rules like A+B = B+A). It can work with non-ASCII notation if the browser supports the relevant entities (e.g. in boolean algebra P Q = P ∨ Q ). It can be applied in any formal situation where the rules can be expressed as equations.