An educational tower of programming language features

The Racket (<a href="http://racket-lang.org/" rel="nofollow">http://racket-lang.org/</a>) dialect of Scheme also provides different levels of a programming language with features of increasing complexity, for educational purposes. In the current version, there are five levels to be used while working through _How To Design Programs_ (<a href="http://www.htdp.org/" rel="nofollow">http://www.htdp.org/</a>). This book is geared toward adults, but Scheme/Racket is also a great language for teaching children (<a href="http://www.bootstrapworld.org/" rel="nofollow">http://www.bootstrapworld.org/</a>). Perhaps this can provide some inspiration for your project.

Very interesting idea.<p>I'm not sure about the goto though (despite/because of it being something I learned as a child).<p>When I used goto it was in the form goto <i>linenumber</i>, but if you're having to create explicit labels to jump to, it would seem easier (to me) to give those labels some explicit structure as loops or functions which doesn't need to be explained at first (they can just act like goto labels) but can be built on later.<p>e.g. the classic:<p><pre><code> 10 print "name" 20 goto 10 </code></pre> in this scheme becomes<p><pre><code> label start print "name" goto start </code></pre> so why not<p><pre><code> loop print name restart loop </code></pre> and then later the label <i>loop</i> could become <i>loop while</i> or <i>loop until</i> or <i>loop with item from list</i>. "restart" makes sense both at the end of a loop and if you wish to continue with the next iteration after a test. Using goto to break out of a loop could be <i>exit loop</i> or <i>continue after loop</i>.<p>I'm not sure what other uses of "goto" you'd expect at this level beyond restarting or exiting loops. If/then seems to take care of simple code branching until you get to procedures.