Thank you for all the answers. They were very helpful. Here are some more ideas

It could be great to have 2-dimensional and 3-dimensional vectors in the "expression-menu". Sometimes my students try to use the binomial coefficient as a vector, and that leads to trouble.

It could be nice to have helpful error messages such as "Did you mean X instead of x". Similarly it could be great to get a helpful warning if they forget the arrow over a vector. (The problem is that \vec {a} and a are interpreted as two separate variables)

It could be useful to have some kind of document-wide setting that caused all variables to be scoped within an exercise. In other words the variables should be reset after each section header.  Alternatively Maple could warn the user whenever a variable is shadowing another variable. ( I tell my students to write "restart; with(Gym)" at the beginning of each exercise, but sometimes they forget and that leads to trouble.)

It would be great to have a document-wide setting where all variables are assumed to be real and all angles are assumed to be in degrees until further notice. (This would probably require trigonometric functions to be redefined)

If the students write "With(Gym):" then Maple could return an error due to "With" being upper case", but the ":" causes Maple to return no output. This error is difficult for new users to track down. it would be nice to have a way to write no output on success, but an error message if the line failed. Is there a simple way to do this?

Kind regards

     Niels