WINDSOR — Windsor Elementary School students and staff members will start the academic year Tuesday in a building so revamped and expanded that it bears little resemblance to what had stood there.

Holly Rennock, who attended Windsor Elementary School as a child, was surprised to see how much it had changed and was excited to tour the school last week with her daughter, Carli Borushko, who will be in fourth grade.

“I like how open everything seems,” Rennock said. “The old school was very dark.”

Rennock was in the new library, which features a wall with floor-to-ceiling windows. The old library had none.

Families got a chance to see the completed school Aug. 29 at an event that combined the annual backpack night —when students can bring in their school supplies — with an open house and a dedication of the $17.3 million project.

“Oh, the library!” exclaimed second-grader Kai Freeman as she walked in and sat on a colorful, stuffed chair that was new. “It’s going to be fun for reading books and sitting on these comfy chairs.”

The Phase 1 addition, which almost doubled the size of the building, opened in February, and then Phase 2, which remodeled the existing school, was started in June.

“For all intents and purposes, it is a brand-new school,” DeForest Area School District Superintendent Eric Runez said. “You would be hard pressed to tell really what was the existing elementary school compared to the new.”

The DeForest school district has experienced “considerable growth,” Runez added, noting 47 more students enrolled over the summer at the K-4 school.

The school redesign included the introduction of a courtyard, created when the L-shaped addition was attached to the old school, which also was L-shaped.

Another big feature of the school revolves around large, collaborative spaces, which are being called family rooms. Two rooms for small-group instruction and a small room for teacher planning and collaboration also were built off the larger collaborative space.

The new gym is twice the size of the old one and has a WIAA regulation-sized basketball court.

It also features a pop-down projection screen and sound system.

The school also has a room with equipment that can help with a variety of sensory needs, paid for in part by a $3,000 donation by the Windsor Parent Teacher Organization.

The school counselor, Stefanie Muller, has her own room where students can sit in fuzzy orange lounge chairs while she teaches life-skills classes.

The room has an area she calls the “Zen Den,” where students can do various activities when they need a short break from the regular classroom.

The school also features a teacher lounge, which had not existed since the original one was converted into a kindergarten classroom.

“It’s a breath of fresh air. It gives us space to do all the things we always wanted to do,” said Principal Roy Bernards about the project. “We were restrained by walls and lack of space. … Kids have changed and our practices need to change and with that comes the environment.”

Mark and Caitlin Bilderback, who live across the street from the school and have a son, Parker, who will be a fourth grader there, have watched the project unfold. They believe one of the project’s big improvements was the creation of a second parking lot.

Before, there would be some 700 people at the end of the day all funneling to one area, Bernards said.

“It was a mess,” Mark Bilderback said.

A $41 million referendum in 2015 funded, among other things, the Windsor Elementary project and the demolition of Eagle Point Elementary School, which also was rebuilt at its existing site in DeForest.