A good way to start your essay would be to identify the central cultural differences that are demonstrated between Jing Mei, born in America, and her mother, of a different generation and a different cultural upbringing. This difference is highlighted well in the following quote:

I won't let her change me, I promised myself. I won't be what I'm not.

Jing Mei says this to herself as she's bawling her eyes out in the mirror because she's not a genius, she's not a prodigy, and she's disappointing her mother and making herself miserable in the process. Instead of a prodigy, she sees an "angry, powerful" girl in the mirror. You can see that this is where American individualism gains the upper hand in her mind—she will be who she wants to be, and she will be strong, she decides. Her mother, on the other hand, was brought up in an earlier time, within a more family-oriented Chinese culture that prioritizes community and making your elders proud. This can be seen during her and Jing Mei's final battle at the piano, when the latter refuses to play:

"Only two kinds of daughters," she shouted in Chinese. "Those who are obedient and those who follow their own mind! Only one kind of daughter can live in this house. Obedient daughter!"

These two quotes are great illustrations of Jing Mei's "American" resistance and her mother's dedication to family pride. Another good illustration of her mother's traditional attitude is when she is speaking with Waverly's mother and complaining about how much her daughter loves to play the piano, flat-out lying and stating that "If we ask Jing-mei wash dish, she hear nothing but music." Her desire to have an accomplished child outweighs any moral impetus for telling the truth.

You have to remember that Jing Mei was born and has grown up in San Francisco in the mid-twentieth century, so she is deeply influenced by the American values at the time; China is a very different place, where collectivism is the norm. This is also the peak of belief in the "American Dream"—that you can come into the country and begin with nothing but rise to the top and live comfortably with nothing but hard work and determination. So, while Jing Mei exercises her "right to fall short of expectations," her mother is falling for the American illusion: that an immigrant can come to the country and be anything they want to be; a child can be a prodigy and become famous with just a little bit of hard work.

But, Jing Mei writes, "Unlike my mother, I did not believe I could be anything I wanted to be, I could only be me."

After introducing the story, author, and timeframe—it was written in 1989—compose a thesis statement that asserts that the historical context of the characters, the cultural values of Jing-mei and her mother, and the juxtaposition of American and Chinese cultures all play a role in the mother-daughter conflict of the story.

First, discuss the historical context. Here you will want to mention the Chinese Communist Revolution, the event that resulted in Jing-mei's mother losing everything, including her home, husband, parents, and twin daughters. Such trauma was bound to affect anyone, but part of the way the mother dealt with her loss was to pin her hopes on America as a land of limitless opportunity. As additional historical context, you should mention the pervasive influence of American media, including Shirley Temple movies and the Ed Sullivan Show. The American media fed the mother's beliefs that her daughter could be one of the "remarkable children."

Next, discuss the conflicting cultural values of Jing-mei and her mother. Jing-mei, being raised in the American school system and in a primarily American culture, wants to be a normal American girl. Although she first likes and fantasizes being "perfect," she soon comes to feel, instead, pressured to be something she's not. She wants her parents to love her for herself, unconditionally, not for having some remarkable gift or talent. Her mother, however, values success—and not just moderate success. Although she tells Jing-mei she only wants her to "be your best," her actions show that she wants Jing-mei to stand out from the crowd. Only exceptional success in America will make up for the desperate losses the mother experienced in China.

Finally, show how Chinese and American cultures clash in the story. The Chinese expectations for child behavior dictate obedience. Jing-mei's mother shows this when she states there are only two kinds of daughters: "those who are obedient and those who follow their own mind!" But the American values of liberty and freedom of expression conflict directly with that childrearing principle.

My answer here is already over 300 words, so you will have to state your ideas succinctly if you are limited to 250 words.

A 250 word essay isn't that many words considering the size of the prompted topic. The essay will still benefit from some kind of thesis statement, but you are going to have to get that done rather quickly to stay around the 250 word mark and provide supporting evidence. I would suggest a thesis statement that highlights the fact that Jing-mei is a typical American child of the time period, which means that her individual freedom and independence is far more important to her than her mother's traditional attitude of a person working to bring honor to an entire family. For the evidence, I would start by showing how Jing-mei initially wants to perform well for her mother; however, her reasons are still fairly selfish. As Jing-mei realizes that her mother's wishes are so far away from her own wishes, she begins to exert her independence. If the essay is really comparing cultural values, I would steer your reader toward seeing that neither Jing-mei nor her mother is wrong. They are just approaching Jing-mei's future from a completely different cultural worldview.