Maths symbols such as comma, other letters
When students are using a phone (Android phones) to enter an answer to a question that is expecting a maths answer, they cannot enter things like coordinates correctly because the option to enter a comma isn't there. Also, if an answer to an equation was, say, y=mx+c, they cannot enter m and c.
If the Abc / 123 little choice box (see picture) was available top right for when students are answering a quiz like it is when we set the quiz up, students could swap between the maths pad and normal input modes if needed. Default to the maths pad but allow the option to change if needed.