Grain Valley voters on Tuesday approved a $3.8 million bond issue to pay for expanding the high school and completing safety and security upgrades.
The proposal won 79 percent of the vote, more than the two-thirds majority required.
The proposal calls for four new high school classrooms, plus infrastructure changes to support future additions. The high school has just over 1,000 students now but expects 1,270 in four years.
The security improvements involve six schools and the administration building. The goal is to prevent anyone from entering a school without first passing through the office.