Author Andrea Cheng believes that "like adults, children deal with a lot of serious issues even if they are not always able to articulate their thoughts".

In the fourth of her Anna Wang book series, The Year of the Three Sisters, the protagonist Wang, a seventh grader in Cincinnati, Ohio, and her friend, Andee, face cultural challenges.

The story starts with Fan, a teenage migrant worker enrolled as an exchange student, with the help of some warm-hearted American parents. When she came to the United States and lived in Andee's house, Anna and Andee not only learned to deal with different personalities from different backgrounds, but also came to understand the life of some 100 million migrant workers in China.

In previous books by Cheng, Anna Wang made friends in a school with few Asian students in The Year of the Book, and learned how to raise the weight of a baby her family adopted from China in The Year of the Baby.

In the third book, The Year of the Fortune Cookie, she then helped one of her teachers adopt a baby in China by visiting China, and during the process, she met Fan.

"As Anna becomes older, so do my readers,"Cheng said. "Fifth, sixth, and seventh graders begin to deal with more complex questions of identity. They may wonder where they really belong, and what belonging really means."

The stories that took place in the Anna Wang series were based on Cheng's real life. Cheng, a Hungarian immigrant who grew up in Cincinnati, married Chinese immigrant Jim Cheng, who was raised in St Louis in the 1960s "when assimilation was the general rule for immigrants in America," she said.

"His parents did not teach their children Chinese; I think because they were worried that they wouldn't be 'American enough.'"

Cheng's three children also have dealt with their identity as half Chinese and turned out to have different connections with China. The son speaks fluent Chinese and has strong connections with China; one daughter doesn't speak Chinese, but shows great pride in her Asian heritage, while the other is more interested in art history.

Anna Wang, a bookworm in the book, was based on Cheng's daughters. Fan is based on a guesthouse worker the family met during their visit to China, and her son's experiences with migrant children in China.

Having given up her own education to support the family, Fan cherished the opportunity to study in America. While struggling with classes, Fan couldn't get along with Andee. Anna Wang was stuck in between.

Fan said she came to the US for success while Andee insisted it would be pointless if she just stayed in her room studying.

"As the book progresses, she sees that differences in culture, personality and upbringing can be bridged, and that people of different backgrounds can still understand each other," said Cheng.

The Year of the Three Sisters, for children ages 6 to 9, will be on sale in both digital and hard copies on April 7.

Lu Huiquan in New York contributed to this story.