McALLEN — Ten-year-old Mackenzie Lopez is learning how to pitch a sale, talk to customers and even advertise. Her favorite technique so far, she said, is to be ready with solutions.

“We stand out there and scream ‘We take credit cards!” she said giggling.

The once shy Mackenzie, of McAllen, is part of Girl Scout Troop 281 consisting of 20 girls ages 5 to 12 led by several moms and volunteers. Starting this weekend the girls are kicking off the iconic annual cookie sale, which is celebrating its 100th year anniversary.

The very first sale of homemade cookies is said to have taken place in 1917 by a troop from Muskogee, Okla., an idea that led to the creation of the famous Girl Scout Cookies, which were first sold under that name in 1933.

To commemorate the accolade, Girl Scouts is introducing the new S’mores cookie – a graham cookie double dipped in marshmallow-like icing and chocolate coating — which will join the lineup of Caramel deLites, Thin Mints, Peanut Butter Patties, Peanut Butter Sandwich and Thanks-A-Lot at $4 per box.

As for Mackenzie, she doesn’t doubt that the new addition will be an easy sell.

“It’s a chocolate cookie, and everyone likes chocolate cookies for some reason,” she said.

Through the sale, the organization hopes to teach girls five main skills, goal setting, decision making, money management, people skills and business ethics. This tends to be the main fundraiser for the year, through which they accumulate funds for their year-long activities.

“It really is a girl-led effort,” said Veronica Garcia, chief development officer for the Girl Scouts of Greater South Texas. “The funds that come in with the cookie sale stay with them and a lot of the times the money is used for multiple purposes. They can choose to give back to the community and do community service projects. They can also choose to fund their own troop activities and their own camping excursions.”

The Greater South Texas chapter encompasses McAllen, Harlingen, Corpus Christi, Victoria and Laredo. In total there are about 18,000 girls ages 5 to 17 who are registered with the organization.

“It can be work, but they know it’s important and they do it with a positive attitude,” said Melanie Lopez, mother of Mackenzie. “It’s easy to do the fun stuff — the paintings and the parade — but it isn’t always easy to do the work. We’ve been able to maintain a group that is dedicated to that.”

Lopez volunteers as a troop leader and said this year the girls decided to use whatever money they raise to lead a beach clean-up project, learn about sea turtles and help protect them.

“They are endangered and they can get caught in fishing nets,” said Julie Ovalle, 12. “If they are stuck there and they’re alone they might die, but if we are there we can help them.”

The girls gain their iconic badges every year for doing different activities according to their age.

“I got a tree badge,” Ovalle said. “And that one is for learning how to help the trees and then you plant a tree and watch it grow.”

Just like the girls have a say-so in the activities they want to spend the funds in, they also set their own goals in how much they want to sell.

On average the group sells about 5,000 cookie boxes per season, Lopez said, and this year they expect to hit that goal again considering the new cookie is getting a lot of attention.

For Lopez the Girl Scouts has not only helped her girls learn about their community, but also gain confidence to tackle everyday challenges.

“It boosts your confidence more because you get to be with all these kids that you probably don’t know,” Mackenzie said. “You get to meet them and you can get more friends… you don’t feel like you are lonely. You have 20-something friends.”