> Can you give an example of a "more complex programming structure" where this would be detrimental to understanding? It is difficult to imagine what kind of k

> Can you give an example of a "more complex programming structure" where this would be detrimental to understanding? It is difficult to imagine what kind of knowledge novice learners will construct while using this tool. I could imagine, for example, that their operational meaning of a variable becomes that of consecutive boxes with values in them. Given that knowledge, how would such a student start to understand a variable in a closure? Will it fit their existing understanding of variables as boxes? Maybe it does, maybe it will not. Maybe they have to deconstruct their understanding of variables first to connect it to their budding understanding of a closure, building a deeper and more widely understanding of variable. Maybe this will be not too much of a problem. Maybe this becomes a hurdle. We don't know unless we try it out, of course. Learning isn't an exact science. I think that dynamic representations like this one are very useful in teaching and learning. However, I would also argue to use these tools with care and conscience. Although it seems to fit our operational view of a program, that does not mean it is a good fit of a novice learner's operational view of a program. Whatever tools we use will influence that operational view. What I want to ask teachers is to evaluate and reflect on the best way and place (in space/time) to use these tools to make learning as optimal as possible.