I have been asked by a foreing student learning English to explain the
difference in the following three sentences.

1. She plays piano.
2. She plays a piano.
3. She plays the piano.

As a native speaker myself, I can try to explain the difference based
on what sounds good to my ear, but what the student is looking for is
a proper "grammatical explanation".

I am looking for an answer approximately one standard 8.5 X 11 page
that explains the difference using proper grammatical teaching
vocabulary.  Any comments about the sentences and additional sample
sentences using the same grammatical points would create a stronger
complete answer.

I will meet with the student soon, so I am looking for a quick
turnaround.  For the right person, this question could be answered
with minimal research likely.

Thank you.

teachinjapan ?

Thanks for your comment.  I am happy that the source I have provided
meets your needs and that I was able to provide it for you promptly.  
As a result of my posting this information in the ?Answer? box, the
question will be ?closed? and you will have an opportunity to post a
final comment on the answer.

The answer contained in my comment has the distinction of being the
first one that I have provided to a customer without having any idea
what I have said.   Under the circumstances, let me supplement the
information in my comment (which I have reposted below) with a few
brief observations of my own.

While I am not a grammarian, I am aware that the use of determiners in
English grammar poses special problems for those who are not native
English-speakers.  And, it seems to me, the example you have posed is
a particularly difficult one.

As I understand it, the choice of determiners for a noun (?piano,? in
this case), depends entirely on the context in which the noun is used.
 The context here can be usefully described as an answer to the
question ?Does she play a musical instrument??

My first impression upon reading your question is that a grammatically
correct and universally meaningful response would be either ?she plays
piano? or ?she plays the piano.?   Interestingly, this impression is
backed up by the unscientific but still meaningful fact that Google
searches using these phrases as search terms come up with almost
exactly the same number of ?hits?:

Google Search: ?plays piano? (62,000 hits)
://www.google.com/search?num=100&hl=en&lr=&q=%22plays+piano%22 

Google Search: ?plays the piano? (62,200 hits)
://www.google.com/search?num=100&hl=en&lr=&q=%22plays+the+piano%22&btnG=Search

(A Google search on ?plays a piano? gets only 3000 hits, virtually all
of them used in an entirely different context, such as ?[she plays a
piano solo.?)


While it probably cannot be said with certainty why the two phrases
appear to equally correct and equally common in English, here is one
possible explanation.

To me, ?She plays piano? is the formulation that is most consistent
with other parallel examples of phrases with transitive verbs, such as
?She plays bridge,? or ?She rides trains, although she prefers to
fly,? and many, many  others. This parallelism may well explain its
popularity and, I am guessing, the possibility that it is the most
comfortable usage for non-native English speakers.

The phrase ?she plays the piano? is, I think, a little harder to
explain, especially to a non-native English speaker, because the
determiner "the" is so often used when the noun refers to a specific
object.  However, this is the version that comes most naturally to me
(and I do, in fact, play the piano) and that appears to have the
longest history.  The best explanation appears to be that one of the
many meanings of the verb ?to play? has long been ?to perform on.? 
For example, the Oxford English Dictionary contains the following
definition and usage example of the word ?play?:

??To play or perform (on a musical instrument)?.  .  .  .?1755,
[SAMUEL] JOHNSON ?. . . as he plays the organ, fiddle, etc.?
Source:  Oxford English Dictionary: Compact Edition (Oxford U. Press,
1971), at Vol. II, page 977

This definition is explicitly carried over into modern American
dictionaries.  For example, the American Heritage Dictionary includes
the following among its definitions of ?play?;

?To perform on a musical instrument (to ?play the guitar?)."
Source: American Heritage Dictionary: Second College Edition (Houghton
Mifflin, Boston, 1982) at page 950.

In summary, in my (nonprofessional) opinion, ?She plays piano? and
?She plays the piano? are both grammatically acceptable and standard
usages as an answer to the question ?Does she play a musical
instrument??.  However, the latter phrase appears to have extra
grammatical "credentials" because of one specific, longstanding
definition of the word "play".


Finally, in order to make my answer ?official?, here is the reposted
substance of my earlier comment:

?Here is a article in Japanese (which I cannot read) that appears to
deal precisely, and in about the right length, with the grammatical
issues involved in the exact English phrases that interest you.?
 
Bilingual Net News
http://www.bnn-japan.com/magazine/oonuma/oonumasensei/0525.html


Search Strategy:

I have answered another question that related to the difficulties
non-native English speakers have with the use of ?determiners? in
English. So, I drew on that experience and conducted Google searches
designed (I thought) to find a focused, brief and coherent explanation
of the use of determiners as applied to the phrases like the three
specific ones that interest you.

When that was unsuccessful, I simply used as search terms part of the
three phrases you provided and came up with the Japanese site that I
provided in my comment.  Here is a link to those search results:

?plays piano? ?plays a piano? ?plays the piano?
://www.google.com/search?sourceid=navclient&ie=UTF-8&q=%22plays+piano%22+%22plays+a+piano%22+%22plays+the+piano%22



Thanks again for the opportunity to answer your interesting question. 
If anything is unclear, please ask for clarification before rating the
answer.


markj-ga

---

Clarification of Answer by markj-ga on 13 Nov 2004 04:16 PST

teachinjapan --

Here are links to other Japanese websites that apparently relate to
the use of determiners in the "piano" phrases that you have mentioned.
 As in the case of the site I linked for you in my answer, I can't
evaluate the relevance of these (although the first one does seem to
be particularly promising), but I am hoping that they will be of some
additional help to you:

Yoshida: Summer 
http://www.yoshida-eigo.com/summer.html

Shonan
http://www.xyj.jp/shonan/19rittou/84.html

Zipang
http://neo.zipang.ne.jp/cgi-bin/home?tochigi01/29

markj-ga

Very fast answer.  Dead on hit for what I was looking for.  Hope to
work with him again.

teachinjapan --

Here is a article in Japanese (which I cannot read) that appears to
deal precisely, and in about the right length, with the grammatical
issues involved in the exact English phrases that interest you.

markj-ga

I neglected to include the link.  Here it is:

Bilingual Net News
http://www.bnn-japan.com/magazine/oonuma/oonumasensei/0525.html

Markj,

The comment you provided is good enough for my answer and I would be
happy to pay you.  This is my first time to use this service.  Can you
please let me know how to change your "comment" to an "answer" so I
can make sure you get paid and I can provide some feedback on you?

Thanks

teachinjapan --

Thanks for the kind words, the five stars and the tip.  I look forward
to working with you again as well.

markj-ga

This may be redundant since you seem satisfied with markj's answer,
but in my experience a British native speaker of English would say
'plays the piano', while a non-British person (especially from the
US)would say 'plays piano'. Elision may well result from the desire
of, especially, Americans to differentiate their style of spoken
English from that of their former colonial masters, as in the British
spelling of 'labour' (US 'labor'), 'neighbour'(US 'neighbor'), etc.

Ocelot,

Thank you for the additional information on my grammar question.