Abstract :
It may be that visual programming languages (VPLs) are best used as a form of “scaffolding” for novices, whereby a graphical environment provides support until such time as novices are able to transfer to a text-based programming language. Before creating such an environment however, we need evidence that VPLs really are of benefit to novices rather than appealing to common-sense conjectures. We have selected a key issue that novices find particularly difficult-recursion-and consider both whether VPLs actually do scaffold the novice programmer in any significant way and whether there is any promise of improvement in the near future. We conclude that recursion is not scaffolded by current VPLs any more than by current text-based programming languages. However, there is some evidence that it is possible to provide support for comprehension, although this support may be impractical if the main use of the representation is that of construction. The more effective representation can be thought of as the application of a sequence of “unfolding” operations. We therefore suggest a representation which incorporates a specific symbol indicating recursion. We hypothesise that novices, given tools of this kind, should benefit from building programs with this structure visible
