Two JS-EDEN sources were used for the 'guided walk' presented in this session: a version of the Shopping construal and a JSPE presentation that outlined the walk from the Shopping construal to a Shopping Game somewhat similar to the Money Math game referred to in the introductory session. To follow the guided walk:

• run jseden.dcs.warwick.ac.uk/scifest
• select the JSPE from the Project List
• copy-and-paste the contents of the JS-EDEN files associated with the two links in the paragraph above into the JS-EDEN Input Window and press Submit.

The thesis behind CONSTRUIT! is that a single construal can be readily adapted in many different ways to create a wide range of educational resources. Such adaptation is indeed relatively easy for a developer (a few small changes to the definitions, functions and actions in a script will typically suffice), but needs to be carried out in a particular way if it is to be comprehensible to the teacher. The idea of this session was to show that adaptations are most appropriately made through a process of incremental adaptation that reflects the maker's stream of thought - in the spirit of a guided walk.

An aside

An attentive reader may be interested in why a revised version of the Shopping construal was introduced for this exercise ... the sketchy explanation that follows may appear out of place in a discussion of 'making construals' for a novice audience. Developers and teachers alike prefer to 'tidy up' their work so that it is easier for the reader and learner to grasp. In reality, software practice is beset by issues that are difficult to address by such tidy practice - changes to software applications and the tools used to support them are a pervasive problem that can make software progressively more difficult to maintain and understand. Inexperienced developers often respond to this challenge by rewriting applications from the ground up, but this is at best a temporary remedy in the face of ongoing change. Making construals aspires to tackle this problem by enabling makers to make sense of what is potentially messy and confusing. The significance of the 'walking' metaphor in this context is that by walking from one place to another we understand the relationship betwen them much more fully than if we adopt a means of transport that takes us directly - and 'neatly' - from one context to another.

The basic shopping construal was adapted by Steve Russ when preparing the Scenes that were deployed at SciFest and at the teacher training course in Athens. The original form of the Shopping construal which he worked with was that documented in connection with the OOC webpage and with WMB's extensions originally proposed for the Welcome page. Manolis Zoulias developed his Greek version of the shopping construal from the original version.

Steve's adaptation involved renaming observables (for instance, 'bill' became 'totalcost') and eliminating their existing definitions from the construal (so that 'bill' was no longer defined). It also involved renaming observables containing text strings and modifying the construal so that his observables, with new names and contents, were substituted for the original observables in the picture observable.

In addition to this, in moving to the scifest variant of JS-EDEN, the form of the Text() construct had been altered and the parsing of conditional ("()?:") expressions changed.

As a result of these changes to the original Shoping construal, and to the JS-EDEN environment, WMB's and Manolis's extensions of the original form of shopping no longer worked.

To overcome these problems, WMB made a revised version of the Shopping construal (differing in few small but critical details) that incorporates SBR's changes but also supports the extensions of the original construal.

This cameo illustrates some important issues for the practice of making and maintaining construals that will have to be the focus for further study in our project.