Indo-European

[Jan Kammert]

I am an 8th grade teacher, and I am planning a unit on the evolution
of the English language.  I have a couple books with some ideas.  The
books talk about the ancestor of English (and all western languages?),
Indo-European.  It seems (Am I right here?) that the idea of the
Indo-European language is a hypothesis.  Since Indo-European was a
prehistoric language, there is no written record of this language, and
certainly no recording of this language.  How do linguists know anything
about the Indo-European language when there is no record of the language?
Before I start this unit in March, I'd like more information.  I don't
want to give my students false information, and I sure want to be able to
explain where the idea of the Indo-European language came from.
Feel free to answer me off-list.  I don't know if my question is so
elementary that I should be embarrassed to ask you all.
<write at scn.org>
Thank you,
Jan Kammert