Friday is a big day for 12 Chicago teens.

Many high schoolers might fill their summer days with friends, family, or an odd job. These 12, however, have spent the past three weeks building bridges and personal shelters.

The rising sophomores and juniors at George Westinghouse College Prep in East Garfield Park are enrolled in a selective engineering program made possible through the school’s partnership with engineering company F.H. Paschen.

Three times a week since July 8, the students have come to Paschen’s headquarters to work on building projects.

This all culminates Friday, when Paschen engineers will put the students’ projects to the test by applying weight to the bridges and blasting the shelters with water.

That made Wednesday, the last build day, crucial.

James Jones and Alfonso Daily, both 15, carefully cut pieces of cardboard with focuses hopefully as strong as their shelter.

Upstairs in the headquarters, Shayla Turnbough, Marinela Figueroa and Aiden Janowitz, all 15, hunched over their model bridge of balsa wood, battling sticky fingers from Elmer’s glue.

By the end of Wednesday, both workspaces were rife with the signs of a long day of hard work: empty coffee cups, scraps of discarded wood and duct tape. There were a few empty Snickers and Starburst wrappers too.

Jennifer Lopez, 15, smiled softly as she gazed at her mostly finished shelter.

“Hopefully, we don’t get wet,” she said.

The scholars all joined the program their freshman year at Westinghouse, when applications open each year since the program’s beginning in 2015.

If selected, scholars remain in the program for the rest of high school. During the school year, they take advanced science and mathematics courses, and during the summer, receive programming from Paschen.

Many of the scholars, like Shayla, applied to the program knowing she wanted to be an engineer.

“There’s so much in the world to do with engineering,” Shayla said. “We get so much experience here with different fields.

There are 17 scholars total, with six each among the rising sophomore and junior classes, and five in the rising senior class.

The rising sophomores built bridges; the juniors, shelters. Seniors like Christian Tovar, participated in a Paschen-sponsored program at the Illinois Institute of Technology earlier this summer.

“I knew that I wanted to do something with math and science — but I didn’t really know what ‘engineering’ meant [before the program],” said Tovar, 17. “This has definitely exposed me to more fields.”

Now, Tovar is working on an independent project, enlisting the help of former scholar and now Paschen intern Justino Martinez, 18, whose three years in the program led him to pursue an architecture career.

Martinez and Tovar helped out the younger scholars as they finished their projects.

In between the stress of wrapping up their projects, the engineering scholars took some time to enjoy a Chipotle lunch with Paschen employees.

In between bites of a burrito, senior project manager Chris Fedro demonstrated for Alfonso and Muyiwa Oni, 15, the technique of cross-bracing using plastic utensils.

Quiet focus seized the room again with the end of lunch.