Edina voters will decide May 5 whether to support the school district’s $125 million plan to upgrade all of its schools, improve security and build an addition at the high school.

The school board voted unanimously last week to authorize the referendum, which marks the first time in over a decade that the school district has asked residents for a tax increase to pay for facility upgrades.

The bond proposal calls for making widespread modifications to all Edina schools to create “flexible” learning spaces where students can work together in groups and teachers can switch seamlessly between working with students one-on-one and working with large groups.

School leaders envision spaces within schools that function a little bit more like those in a modern office, with movable furniture, common work spaces, space for large groups and areas where partitions could be easily erected or taken down.

The proposed project also calls for building a 70,000-square-foot addition to the high school, a plan being driven by the district’s plan to move ninth-graders from the middle school to create a more traditional high-school and middle-school experience.

Under the plan, a multipurpose activities center would be built at the high school to accommodate physical education classes and to provide meeting spaces for extracurricular groups and room for students to work on projects like robotics.

Some residents who live off Creek Valley Road have expressed concern about increased traffic and noise should the district extend the road to connect to a new parking lot built to accommodate the new activities center.

“To open that road up would be a real catastrophe from our standpoint,” said resident Walter Meadley.

District officials said they have had productive talks with people in the neighborhood and hope to have an alternative proposal for parking-lot access in coming weeks.

If voters approve the referendum request, the owner of a typical $400,000 Edina home would see an annual tax increase of $324 a year, according to preliminary cost estimates. Construction would start in 2016.

A December survey showed that 61 percent of likely voters would support the referendum.

“Ultimately, it’s up to the voters,” said school board member Sarah Patzloff. “I hope residents take the time to become informed and engaged in the process.”