Kids would then create their own 1/2's by clicking on the Boy/Girl to get them to change and if you gave them the fraction tool they could create many more.
Looked at using a Player in Etoys, as it is easier to create an interface to select those using a Player variable by simply clicking on them (actually two clicks, one on the player variable and the second click on the object).
Okay as I write this another method comes to mind, I could use two holders (or one) and place the objects to switch to (on MouseDown or MouseEnter) use those two objects (aka Players) for the fraction box. Ran into some problems and created some issues in tracker (fortunately we have Bert and Karl working hard to fix issues). Another thing I tried (my original idea) was to have one object that was programmed to switch costumes (the graphic that is displayed on the screen). I think the an interesting set of lessons to develop would be one around the programming/development process but that's much harder and besides folks much smarter than myself are working on it (ex: Mark Guzdial and his excellent site for teachers, one of my way too many side projects is to create an Etoys version of his course, have one or two projects but a lot of work still to do). One of the key lessons if I ever finish the Etoys course should be that frustration is normal and to be expected, if your not getting frustrated and failing your not trying hard enough (well it's late and I am frustrated so I thing I have tried hard enough for tonight ;)
Comments and suggestions always welcome.