I am a highschool teacher and we just started using Maple. It is a great program, but the students  had a few problems with the worksheet-mode in the editor. Here is a list of small problems that are hopefully easy to fix.

In text editors such as Word you can highlight a piece of text and select "insert->equation" to turn the text into an equation. Maple doesn't supprt this, so if the students have written an equation in textmode, then they have trouble turning it into math-mode. (the answer is: highlight, ctrl-X, F5, ctrl-v but that is difficult to guess for beginners)

Once in a while the students place two equations next to eachother with no space in between. When this happens they cannot place the cursor between the two eqations, and therefore they cannot place a newline between the equations. In other words the two equations are glued together. (I think that you can solve this by pressing f5 in the right place, but it would be better to mirror the behavior of word)

It would be great to allow the user to delete the pink error messages by pressing delete. Sometimes the students use math mode to write text inside a large paragraph and the result is an error message a few lines below. This error message cannot be deleted unless you trace down the math field and delete it. In one situation a student had deleted all the letters in the math field, but the error message could not be deleted until the empty mathfield had been found and deleted. (One solution is to highlight all math fields on the page whenever the user is editing text in math mode. That would make them easier to find and understand)

If a student pressed enter or alt-enter inside an equation in worksheet mode, then the student stays in worksheet mode after executing the equation. I would prefer to switch to text-mode after pressing enter. This would mirror the behavior of word. Sometimes the students end up writing a long paragraph because they expect Maple to mirror the behavior of word. Once the text has been written in math mode then it is difficult to convert it into textmode again (This requires highlight, ctrl-X, F5, ctrl-v)

It would be great to write an equation that isn't meant to be executed by the kernel.  In other words the equation should only be for display. You can solve this by writing ":"  at theb end of the equation, but that makes the math look weird. It would be nice to have a way to do this.

If mac users havent installed a printer then they cannot export to pdf. It would be great to solve this problem (or at least write a helpful error message)

All of these problems are beginner problems, but if I you want to sell Maple in highschools then I think that you can gain from focusing on making Maple approachable so that the students have an early succes-story with the program. In my class we switched to Maple from another math program, and it was a hard sell because the other math program had an easier editor.