Two Stony Brook teens have perfected how to turn lemons into lemonade for a worthy cause.

Maddie Mastriano, 17, and her younger brother Joseph Mastriano, 14, started off just wanting to sell lemonade outside their home one hot August day in 2013. At the time, the pair never imagined their venture would grow, or how it would grow.

The first year they thought of splitting the few dollars raised between friends, but their mother suggested donating it to charity. Since then the Mastrianos and their friends have raised $36,000 for Stony Brook Children’s Hospital with their Three Village Kids Lemonade Stand — $20,000 of that amount from this past summer alone.

Laura Mastriano said her children caught the fundraising bug after the first time they handed over the money to Stony Brook Children’s Hospital, so they decided to make it a yearly tradition.

Formerly known as the S-Section Kids Lemonade Stand, the booth attracted hundreds of residents from all over the school district and even local celebrities to their home in 2016, according to Mastriano. The event was moved to the grounds of R. C. Murphy Junior High School, where Joseph is a student, in 2017, and 500 people attended over the course of another hot August day. Besides lemonade, the kids have expanded to offer food, activities and live music. Town of Brookhaven Supervisor Ed Romaine (R) presented them with a proclamation, and celebrity chef Barrett Beyer of “Hell’s Kitchen” made an appearance and even some gourmet lemonade for attendees.

Mastriano said it was necessary to move the lemonade stand to the school grounds due to its growing popularity, and it made sense because of the number of student volunteers from the Three Village Central School District. Maddie and Joseph approached school board trustee Inger Germano about the idea, who said she thought it was a good plan, and the district agreed to host it.

“We thought this would be a great opportunity to get more children involved, not just from the S-Section [neighborhood] but from the Three Village community and the school,” Germano said. “I think it was the right move.”

Courtney DeVerna, 7 years old, has been volunteering at the stand for the last three years, having visited the stand with her mother Lisa since she was 2. As soon as Courtney understood it was a fundraiser, she wanted to help and even practices her lemonade pouring before the event.

“It’s really fun and exciting because you’re waiting to do it for a while, and it’s for a good cause,” said Courtney, adding she looks up to Joseph and Maddie. “We’re giving the money to the children’s hospital, which makes me more excited.”

The siblings are always coming up with new ideas, according to their mother, so to help reach the pair’s 2017 fundraising goal of $20,000, the brother and sister solicited the help of sponsors, including fast-food chain Chick-fil-A. The idea came to them after noticing that many fundraisers partnered with local companies.

Recently, Maddie, Joseph and friends participated in the Three Village Holiday Electric Light Parade to promote their fundraising venture. Joseph said during the school year they work on their website, research ideas on how to make the next event better, ensure everyone who helped is thanked and sign community service letters for the 150 student volunteers.

“We know how busy everyone is, and we are so thankful and glad they helped,” he said.

Maddie, who is a senior at Ward Melville High School, said she plans on continuing the tradition even though she will be away at college next year. The siblings have already set a new goal, hoping  to eventually raise $100,000 in total for the Stony Brook Children’s Hospital.

“Next year Joseph will take on a bigger role in the planning while I am away, but I know he has things under control and actually has really great ideas already,” Maddie said. “We will do whatever we have to do to make sure this community tradition is an annual tradition. We are thankful for the community, for the support and for the opportunity to come together to turn lemons into lemonade together for the Stony Brook Children’s Hospital.”

Their mother said they each bring different talents to the table. Maddie hopes to major in communications when she attends college, and Joseph is good with numbers.

“That’s where they complement each other,” their mother said. “He’s business, and she’s the communications part of it. It’s pretty fun to see that.”

Joan Alpers, director of Child Life Services at Stony Brook Children’s Hospital, said Joseph and Maddie are creating a legacy in their district.

“Both of them are outstanding, mature, bright and polite kids, and very humble for everything that they do,” Alpers said. “They’re so professional to groups and the community. They’re able to pull off putting together something that is much larger than most people their age could pull off.”

Their mother said she and her husband Joseph still can’t believe how popular the Three Village Kids Lemonade Stand has become.

“I have to say that I am beyond proud and blown away by all their efforts,” the mother said. “It really was a small lemonade stand that has grown into a beautiful community tradition, and it’s something that I am not only proud of, seeing what they’ve accomplished, but proud of what all of these kids in Three Village have been able to do. It’s contagious wanting to do good for others, and I think that starting so young really has infected others to want to do good for the kids in the hospital. It’s a pretty incredible thing.”

For more information, visit the website, www.threevillagekidslemonadestand.com. The next Three Village Kids Lemonade Stand is scheduled for Aug. 8, 2018.