How far should I help students with learning extracurricular skills? I am currently a teaching assistant for both master and PhD students. Part of my work included helping and supervising them during several lab experiments (physics). One task of the lab experiments is to write a program to numerically calculate values and simulate them afterwards. The students are allowed to use any programming language they want to use (except stuff like Brainfuck and Whitespace, of course), as long as they provide the source code with the result.
While the master students are not having any problems with the problem, I got was asked by the PhD students if I can help them do the programming in Excel, as that is the only thing they can use and know for "programming".   

How far should I now go and help them? I know that doing the task they are assigned to is impossible to do in Excel, but they never used any other language or programmed themselves. I am able to teach them how to achieve the programming goal, but based on their current knowledge that will take a lot of time, which I also need for my own lab tasks. Should I thus simply tell them to drop the course, or should I try to help them, and if yes, in which extent?
If you are a TA and have questions about what to do, almost always the first thing you should do is ask the instructor.  The instructor should clarify exactly how you should be assisting them, and what the prerequisites for the course are.  I would be wary, as a TA, of suggesting students to drop the class.