Consider the architect in the time of COVID-19. Locked down. With a 3-year-old.

Alex Gilliam and his wife, Renee Schacht, who run a small, nontraditional architecture practice called TinyWPA, have been working from their Brewerytown rowhouse since Philadelphia imposed a quarantine in mid-March. Or rather, trying to work. Like parents everywhere, their days have been hijacked by childcare responsibilities, even though they’ve set up shifts for work and parenting. With no daycare, no playground, and no playdates to fall back on, their attempts to occupy their energetic son, Scout, were testing their imagination and patience.

A month into the crisis, Gilliam had an epiphany: If Scout couldn’t go to the playground, he would bring the playground to Scout.

It started with a few scraps of lumber. Gilliam pieced them together to form a seesaw. He grabbed one of those notorious “Cash for Houses” signs and turned the plastic rectangle into a seat for a swing. Then, with the permission of his next-door neighbors, he built a crude platform on top of the fence that separates their yards, and a ladder to access it. After the neighbors, Sarah Peoples and Jacob Roller, brought back branches from a nature walk with their daughters, Josephine, 6, and Eleanor, 3, Gilliam wove them into a railing.

A treehouse began to grow in Brewerytown.

Scout was delighted. So were the two girls, who immediately climbed into the hideaway. Gilliam’s ever-growing treehouse — now at eye level with his home’s second-floor windows — is on the verge of forming a canopy over the two yards. But the mammoth arts-and-crafts project has also become a lesson in how to make the best of the pandemic. Not only has the process of constructing the treehouse proved educational for all three children, it has given them some much-needed autonomy at a time when they’re cooped up 24 hours a day with their parents.

“I always had it in the back of mind that I would build Scout a treehouse,” Gilliam explained. The quarantine simply accelerated the schedule.

Before the virus, the two families had joked about cutting “a Hobbit door” in the fence between their yards so the three children could go back and forth on their own. While the need for social distancing now precludes such close interaction, the treehouse serves as a safe bridge between the two families. When Scout is using the platform, he can see his friends playing in their yard. He’ll sometimes lower a bucket attached to a rope, pretending to be fishing. Then it’s the girls’ turn. Scout retreats to his yard and they’ll declare that the treehouse has become a pirate ship. “If they can’t actually be together, at least they can interact this way,” said Peoples, a sculptor.

Creating the means for Scout, Josephine, and Eleanor to have a socially distanced playdate wasn’t exactly what Gilliam had in mind when he first began hammering two-by-fours together. But the concept emerges directly from his professional interests.

Unlike architects who design buildings for clients, Gilliam has devoted his career to teaching children how to design and construct things for themselves. While he thinks that everyone should know how to use a power drill, his real mission is to expand conventional ideas about play, by encouraging children to actively shape their environments. That kind of creative and imagination-driven activity helps develop important life skills, said Gilliam, an early proponent of a movement now known as “free-range parenting,” which holds that our culture’s fear of risk stunts children’s emotional growth and causes anxiety.

His firm, originally called Public Workshop, has organized construction workshops for schools and nonprofits around the world. Gilliam was in Taiwan when the virus emerged, running a program that brought middle school students and senior citizens together to build street furniture where both groups could linger. He’s also taught in the Philadelphia and Camden School Districts, using his workshops to teach leadership skills and promote social interaction.

“We’ve seen a lot of behavioral and academic improvement come from this approach,” Gilliam said. “With all the emphasis on high-stakes testing, there is less opportunity to be physically active." Teaching construction skills "gives kids a chance to be creative. It feels good to be using these gross motor skills, especially for kids who don’t succeed in traditional school settings.”

Still, he never expected to be instructing a 3-year-old on the fine points of wielding a hammer. But Gilliam felt he couldn’t build the treehouse without involving Scout in the process. When the hammer proved too heavy for the toddler, Gilliam showed him how he could get the same result by holding it sideways with two hands. “He can’t use a drill yet, but he could help pull the trigger,” he said.

Gilliam admits he was nervous when he first saw Scout climb 7 feet on the steep, center-post ladder into the treehouse. “We knew we were taking a risk letting him climb it on his own,” he said. Yet, in a few days, Scout became a pro, “refining his motor skills” to scamper up and down.

Peoples and Roller share a conveniently similar philosophy about parenting. Their children attend a Montessori school that encourages students to learn by doing for themselves. “Both of our children are very independent, strong-willed, spunky and wild, which is exactly what we need our girls to be,” said Peoples.

Every day, the two families add something new to the treehouse. Gilliam’s high-design instincts kicked into gear at one point, and he designed a butterfly-shaped canopy, reminiscent of the jaunty roofs that were popular with midcentury architects. There’s an improvisational, Rube Goldberg quality to the construction, with extensions jutting out from all sides. Most of the materials are scavenged, said Gilliam. “We’re trying to be pretty good about being quarantined, so there’s no going to Lowe’s.”

For overworked parents who have reluctantly plopped their kids in front of screens to get their work done, the treehouse project may seem beyond their abilities. Gilliam notes that he’s also working 50 hours a week, instructing students by Zoom.

But building a DIY backyard playground could save parents time in the long run if it makes their kids less needy. Parents can start small, perhaps with a tree swing. Gilliam’s website includes step-by-step instructions. No matter how the final product turns out, the construction process should keep them busy for a little while.