The student should get in and start hacking away at some non critical part of the code base. Perhaps the UI, or some reporting or tests. Something it's OK to break for a day or two.
Pair them up with a more experienced developer and make sure they do code reviews. Discus the code and talk about what went right and what went wrong.
Even as a beginner you can tackle small snippets of code using the basic control structures.
Sadly, this is how programming books used to be written. Case in point: about a decade ago in high school we learned programming from a book called C by example. It had a handful of well thought out programming exercises after every section. A few years later I went looking for the book to give to a friend who was starting out. Lo and behold, in an updated version the exercises were all removed! It's mind-boggling that somehow the publisher thought removing the exercises was adding value to the book. Perhaps your average reader feels exercises makes a book seem too technical, so they skip it for the Learn X in Y hours style books? Nowadays you can't find good programming exercises outside of a dry textbook.