Caterina Scorsone Marks 4½-Year-Old Daughter Pippa's First Day: 'Little Babe Started School'

Grey's Anatomy actress Caterina Scorsone explained that the in-person schooling came with "masks and lots of protocols"

Caterina Scorsone is celebrating a milestone with her daughter.

On Tuesday, the Grey's Anatomy actress, 39, wrote on Instagram that her 4½-year-old daughter Pippa started school.

"This little babe started school today. With masks. And lots of protocols. In the grand scheme of things, we figure it's good that she's there learning, playing, safe from zombies," Scorsone wrote alongside a photo in which she pretends to bite Pippa's ear during a selfie.

Scorsone is also mom to two other daughters — Eliza, 9, and Lucky, 20 months — whom she shares with ex Rob Giles.

In July, she told Parents magazine about bonding with each of her kids individually. One of her favorite things to do with Pippa is to "go around the neighborhood, walking and talking about her school and about the flowers that we see." Scorsone said her middle daughter, who was born with Down syndrome, is beginning to expand her vocabulary.

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"One thing many people don't understand about Down syndrome is the hypotonia, the decreased muscle tone. The musculature of Pippa's mouth and tongue is less developed, so it took her a little longer to develop expressive language," she explained at the time. "But we taught Pippa sign language early on, and sometimes she'll still sign to get her point across."

"Her receptive language has always been strong, so she understands more than many might assume," she added, "and now her vocabulary is starting to blossom."

As Scorsone told PEOPLE back in October, Pippa is "perfect exactly as she is" and "so are you, and so am I. The only way we lose sight of that perfection is to look for it somewhere else." Reflecting on raising Pippa at the time, the star said her "difference lit a match in my life and in the life of my family."

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"When my daughter Pippa was born, I was scared. I didn't know anything about trisomy 21, the name for the occurrence of a third copy of the 21st chromosome, better known as Down syndrome," she said. "... I didn't know anything. All I knew about Down syndrome was that people were afraid of it, so I figured I should be too."

The star explained how she then quickly shifted her perspective, seeing any of Pippa's differences as beautiful individuality like anyone else's unique attributes. Scorsone said Pippa's arrival "cracked open a door in my life" — for the better.

"It suddenly became crystal clear," she said, adding, "There is no standard, objective, perfect human being. The metrics of perfection are arbitrary and imposed in the service of those who fit them. My daughter is perfect. Exactly the way she is."