It is important to get your bases before you diversify your skillset. Rather than learning too many things at once, I recommend you work double time on learning plain C or C++. as per your class (but as said working overtime, trying stuff on your own etc. in C language). When you start being proficient with C, you'll see that much of this knowledge "ports" to java or python, for example.
If you are really jumping at the bit, maybe javascript (or even javascript with jquery) would be a good parallel learning stack, as it is both similar and different enough that you have less risk of mixing things as with c and java. (Also, javascript requirements are less, mostly you need an editor and a web browser...)
Edit: Why learning C/C++ is important
A comment to this response dismissed the interest of learning "a language he'll never use at work" and spoke strongly about the "uselessness of pointers". On the surface these arguments hold some truth:
- There is, probably, a less than even chance [a] that anyone starting a career in programming in this millennium will have a direct use of C/C++ as part of his/her professional endeavors
- Pointers are a powerful but dangerous things, most languages are the better for sheltering their users from such bug-producing devices. In fact some languages like java were explicitly created to void (pun non intended) the need for pointers!
And yet, in the face of such technically correct observations, many industry observers -who are more qualified and eloquent that I- persist in their recommendation that C/C++ should continue to be included as one of the founding blocks of a practically-oriented education in Computer Science. They also point out the relevance of the C language in of itself, as applied to various areas of the industry. I'll let such sources speak for themselves, one can find various forms of their argument online. I'd like however to present briefly why learning the language makes sense for the OP and other young people seeking a career in the field.
- He is readily engaged in this class and might as well succeed at it!
That's obviously a very weak argument with regard to the question of relevance of C/C++ "in the absolute", Yet, a valid and practical argument to him. Getting good grades and the respect of his professors may eventually afford him many additional opportunities.
- A semester long class, in any language is hardly enough exposure that it would irremediably make him unfit to learning anything else. There is therefore, in the worse of cases, no harm done. However, and thanks to C's relative simplicity and focus on close-to-the-machine concepts, this should be enough time to provide him with an understanding of things at this particular level of abstraction.
- If nothing else, this will provide him with elements of syntax broadly used elsewhere; for better or worse, C and C-like syntax have permeated so many languages.
- A well rounded university CS cursus will include classes on topics such as Operating Systems or Compilers and such courses will either directly use or make references to the language. Here again one could argue that the recipients of such an education rarely design a full blown OS or a general purpose language during their professional life and that learning either of these is therefore a waste of time. Here again: direct usage of a particular knowledge or skill isn't the sole criteria for relevance.
- The purpose of a formal education is to learn meta skills and to acquire a broad culture which will help adapt to (and in some cases shape) the evolving set of technologies associated with CS and IT. Learning a particular language can (and will!) be done at any time during one's career, and such often done by reading books, practicing alone and other self-teaching approaches. Such learning is made easier when applied atop solid foundations rather that atop a somewhat sophomoric grasp of concepts as is sometimes observed in people who learned too much too soon (and who focused on learning the operational interface of things rather than their essence).
[a] "less than even chance": this is just wild guess. I didn't attempt to quantify this scientifically by any mean, I'm just stating my agreement with the fact that a minority of the next generation of coders will have direct need for C/C++ and an even smaller majority will be frequent practitioners.