One of mine went through a phase of trying to fit everything into minuscule spaces as well, with a minimum of writing. We had repeated conversations about math as a language, and as communication, and eventually got to the point where sufficient work is shown--though there is still a tendency to write just a bit smaller than a presbyopic adult can quite read comfortably. And yes, it was about wasting paper.

...pronounced like the long vowel and first letter of the alphabet...