I am interested in developing an app for students that are starting a grade career involving mathematics. It is a real problem that they start with almost no knowgladge of basic mathematics and there is no time to teach it in the curricular courses. Is it possible to help they learn some basic properties of operations with real numbers like product, sums and exponents using an app? They are really confused about which operations are "allowed" and which are not. For example when is it correct to cancel two "x" or some doubts that involve operator's precedence. I know that behind this, there is a lack of understanding about the meaning of the equations they write. Do you think is it possible to impart this knowgladge with an app? Do you know any existing app that aims to do this? (i could not find, but I am not good at research). Sorry for my bad english.