The actors have been split into three groups, with each group performing one of the three shows to be staged this weekend.
Our junior reporters paid a visit to one of the groups this week. They met the director, music director and the three leading cast members. Let's find out how their rehearsals are coming along ...
Pretend to love
Francis Ng, 15, plays the lead role, Professor Harold Hill - a fake music teacher who scams the citizens of Iowa, but ends up falling in love with Marian, a piano teacher. Francis says he joined the musical because he wants to improve his acting and singing skills, as well as polishing his spoken English. He loves the experience so far, and says it's "a perfect opportunity" for him.
However, being the protagonist is about more than just the glitz and glamour. Acting is all about breaking out of your comfort zone, and playing someone you don't know. "One of the greatest challenges for me is the love scene with Nicole [who plays Marian]," Francis says with a sheepish chuckle. "I have never been in a relationship before. So grasping the intense passion of being madly in love is proving to be a real challenge - let alone conveying it convincingly on stage."
An actor must be a jack of all trades when it comes to putting on shows; Francis has experience in every aspect of performing arts - from acting to dancing and singing. He has performed legendary Hong Kong rock band Beyond's classic song Boundless Oceans Vast Skies. Recently, he treated his school to an a capella rendition of the Angry Birds theme tune.
Francis says his ambition is to study vocals at the Hong Kong Academy for Performing Arts.
Francis Ng (left), Nicole Hurip (centre) and Jocelyn Tsang Choy-yin play the three leading roles in the show The Music Man Junior.
Meeting the director and music director
The Music Man Junior is directed by stage veteran Professor Oliver Lo See-yin, with music by Li Si-lai. Both of them have played an important role in the musical's success.
Lo, who spent years teaching music in the United States, says the musical is very popular in America, but it receives little attention in the rest of the world. "There are already two movie versions of it in the US," he says.
Lo used to works as a primary school teacher, so dealing with children is nothing new to him. Yet he sometimes finds it challenging. "You can't tell them off if they make mistakes," he jokes. Lo has been very impressed with the progress of the young actors, and he has found them to be very talented.
However, deadlines are an issue - Lo has only three weeks to train three different groups of actors. "They may not be ready now, but when they perform onstage, they will be ready," he says. Lo likes the tight schedule because it means there is not enough time for the crew to prepare. He believes that makes the show's performances more natural and impromptu.
Li started working with the children back in May. She says that intensive training helped to give the children a glimpse of what a musical looks like.
She thinks dealing with children of all ages is the main challenge she faces. Her goal has been to help the young actors build up their confidence, she says.
"Some children are as young as five years old, while some are seventeen," she says. "But the problem wasn't so bad at all. For the older ones, I tend to assign them tasks that are more challenging - for example rapping and playing the lead roles - leaving the younger ones with relatively easier tasks."
Off-screen brother and sister
Nicole Hurip, a 17-year-old student at Maryknoll Secondary School, plays Marian, a piano teacher with whom Professor Hill falls in love. She is Chinese, despite her surname suggesting otherwise; her grandfather adopted an Indonesian surname when her family, who used to live in Indonesia in the 1960s, faced racial persecution.
Nicole may tower over most of the cast members, but she's delighted to work with them. "I love kids," Nicole says. "For the younger ones, I pat them on the shoulders. For the big kids, I get along with them OK." She says having a little brother helps her understand children better when they are young. Her younger brother, Ethan, is also in the show; he plays Winthrop, the brother of Marian. "He's 10 years old," she says.
Ethan was the first one of them to find out about the musical, and later Nicole decided to tag along.
Besides making new friends, Nicole has also learned a lot of new skills. "This is the first time I've joined an activity outside school," she says. "It's been a good learning opportunity."
Speaking of performing her love song with Professor Hill, played by Francis, Nicole flashes a cheeky smile. "It's hard not to laugh," she says.
Preparing for university, Nicole is hoping to study in the US. Although she loves singing, she plans to pursue a journalism and communications degree at university.
The majority of the cast of Opera Hong Kong Summer School - aged from five to 18 - is very young. Yet all of them are very talented.
Jocelyn Tsang Choy-yin is only 10 years old, but her star quality and stage presence are undeniable.
She plays one of the main characters, Jacey Squires, who is a member of the school board.
Jocelyn finds her role quite interesting because, as a male character, she has to dress up as a boy and wear a suit. Although she knows the transformation is odd, she still finds it fun to play. Jocelyn says she finds it hard to stop herself from laughing during rehearsals.
The Music Man Junior's cast have to be comfortable about mixing with performers of different ages. Jocelyn says it can be a little difficult to get along with the younger ones, but communicating with the older cast members is not a problem.
Other than singing and acting on stage, Jocelyn also enjoys reading. Her favourite books are the Harry Potter and Hunger Games series. She says she is one of those book lovers who can happily read the same book over and over again, but never get bored.
Actress Jocelyn Tsang Choy-yin (centre) rehearses with other cast members.
The Music Man Junior musical is on this weekend. There will be two performances on Saturday - at 3pm and 8pm - and one on Sunday at 3pm. For more details, click here.
Young Post has nine pairs of tickets to give away. For a chance to win, send your name, age, contact details and show (in order of preference) to firstname.lastname@example.org ... now!