- Specularity in Algebra
- Experiencing Equivalence, but Organizing Order
- Examples, A Missing Link
- Moore and Less!
چه خالی است a جای (“a” is greatly missed) is the third of a series of papers about the different roles of letters in algebra, the first one was What a delicious a! (a چه خوشمزه است) and the second one, What a silent a! (a چه ساکت است). This one-page paper gives some example of how different and mostly ambivalent uses of the so-called “blank square” or the like in arithmetic could be a source of confusion when children start to use letters in algebra.