Sute, basics are basics, but why not just install QtCreator? Modern day C++ with modern day tooling, GUI, that in all likelihood runs on the machines the students have.
On top of that, regular old Qt is still one of the most fully featured GUI frameworks, QtQuick is mostly used for mobile and embedded, even though it also works on desktop. Lazarus or Tkinter aren't better choices for starters, I say as someone who used both.
But, even if you don't like Qt, QtCreator is still a great IDE. No need to keep using a Dosbox with Turbo C++.