MILFORD — Sometimes a serious administrator, sometimes a goofball, Principal John Foss has won the hearts of his students and staff at Jacques Elementary School. On Friday, the school celebrated “Mr. Foss Day” with fun and games in honor of their retiring leader.

Signs all over Milford, from the Oval to County Stores, posted messages in honor of Foss wishing him well in his retirement.

Foss has been at the helm of Jacques Elementary for the past 11 years, and has worn many hats — literally — in his role as principal, often dressing up in whacky costumes from pirates to flower pots to the tooth fairy, in part to entertain the kids, but also to engage them.

“He is as much of a kid as they are,” said his administrative assistant Karla Lessard. “He's a goofball. I've actually seen him rolling around on the floor laughing with the kids.”

Foss got into education because he had struggled so much himself. It wasn't until he was in eighth grade that he learned how to read, but with his mother's persistence, he went on to college and then graduate school and his focus remained on reading because he understood what kids who had trouble were going through.

“He is the role model every parent wants to see at their children's school,” said teacher Shannon Mason.

His first job was with the Rye School District, and from there he went over to Weare. He landed in Milford in 2001 and quickly became indispensible to both the students and staff.

Every kid in the school, which educates students in kindergarten and first grade, gets a chance to eat a one-on-one lunch with Mr. Foss during the year, said Lessard.

“He knows all of their names,” said his former administrative assistant Linda Pelchat, who worked with Foss for seven years. “He brings so much openness, so much caring to this school. One of the gifts God has given me is my time working with John Foss.”

Compassionate, spiritual and selfless are some of the words staff members used to describe Foss on Friday as he ran from the gym to the fields to the new gardens behind the school named “Foss Fields” and played games with the kids. There was a relay race in which every student had to dress up like Mr. Foss in his daily “uniform” that consists of a blue dress shirt, glasses and a tie. There was a station where kids threw sponges made to look like pizza through a mouth cut into a blown-up photograph of Foss. There was even a lunch line relay in Foss' favorite room in the building — the cafeteria.

But the best part of the day for Foss was when the students sang his favorite song “You're a Grand Old Flag.”

“I actually made them sing it again so I could record it on my phone and play it for my father-in-law,” said Foss.

When Foss retires at the end of the June, he'll be starting a new life, bugging his wife — whom he calls his anchor — and teaching at Rivier College in Nashua. He'll also be serving as the town moderator in his hometown of Weare.

But the folks he leaves behind are going to miss him terribly.

“I'm very sad,” said teacher Jodi Alperin. “This is my first year teaching here full-time and it's just been the best year ever. He is going to be so missed.”