Twentieth century American science fiction was originally almost entirely confined to magazines; at some points there were dozens of monthly science fiction magazines publishing short stories and serialized novels.  Not until the 1940s and 1950s were novels published in book form, and even today many prominent writers have their novels published as serials in magazines before appearing as books.  The most prominent science fiction magazines in America today are:

Isaac Asimov’s Science Fiction Magazine (www.asimovs.com)

Analog (www.analogsf.com)

The Magazine of Fantasy and Science Fiction (http://www.sfsite.com/fsf/)

A classroom or school library subscription to one or more of these magazines can provide students with a good view of the variety of modern science fiction: if one story does not appeal the next one might very well, with the student losing less than an hour of time instead of the several days that might be lost if he or she finds that a particular novel doesn’t appeal.