MINNEAPOLIS (WCCO) — A Prior Lake teen is set to graduate this Saturday from high school at just 15 years old.

Grant Rubietta zipped through grades K-12 with online schooling at Minnesota Connections Academy.

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He is the youngest graduate the school has seen.

Rubietta will serve as one of the graduation speakers for the class of almost 300 students at a ceremony to be held at the Minneapolis Convention Center on June 10.

Grant Rubietta (credit: CBS)

Grant’s mother, Tracy Rubietta, struggled early on with what to do about her super smart son.

“He was already reading and writing at 3 [years old],” Tracy said.

Grant’s parents enrolled him in Minnesota Connections Academy, where students learn online with help from instructors.

“By the end of the year I had finished kindergarten and first grade,” Grant said. “And I did that for second and third grade, and fourth and fifth grade.”

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Grant was in a sixth-grade curriculum by the age of 8. He slowed down to just one grade per year after that point.

“[We’re] extremely proud,” Tracy said. “We’re happy he’s doing so well, and it’s just pretty cool.”

Rubietta said she is also proud of her son for maintaining interests and friendships outside of his schooling, and for remaining humble about his achievements.

“I’m feeling excited,” he said. “I worked really hard to get to this point and I’m very happy.”

Grant’s drive rubbed off on his 13-year-old sister, Isabella, who will also graduate at 15 from the same school.

The advice he will offer to his peers when he gives his commencement speech? Believe in yourself.

Grant plans to attend the University of Minnesota next year, where he plans to study biology.

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He can’t drive yet, so his parents will need to take him to campus for class.