Volunteer Kate McCormack, left, and student Indira Martel Tarrant slide a window frame through a jig to apply foam tape Wednesday at Winthrop Middle School. They're building a window insert that helps a home retain heat and make it more energy efficient.

Students Blake Gambrel, left, and Noah Audet place a mullion at the center of a wooden frame Wednesday at Winthrop Middle School. They're building a window insert that helps a home retain heat and make it more energy efficient.

Volunteer Kate McCormack, left, and student Indira Martel Tarrant prepare to put foam tape on the outside of a window frame Wednesday at Winthrop Middle School.

Student Noah Audet drives a fastener into a corner of a wooden frame Wednesday at Winthrop Middle School.

Volunteer Kate McCormack, left, and student Indira Martel Tarrant prepare to put foam tape on the outside of a window frame Wednesday at Winthrop Middle School. They're building a window insert that helps a home retain heat and make it more energy efficient.

Students Blake Gambrel, left, and Noah Audet work with volunteer Andy Wess as they assemble wooden window frames Wednesday at Winthrop Middle School.

Student Noah Audet drives a fastener into the corner of a wooden window frame Wednesday at Winthrop Middle School.