Now let's view a first-grade class as they extend this lesson to a similar activity with congruent triangles.

Ms. McAlear teaches a first-grade class in West Roxbury, Massachusetts. In this video segment, students cut their squares into two congruent triangles and discuss why these triangles are halves. They then work in pairs to cut four squares into triangles. They rearrange the triangles until they have a design they like, and then glue their pieces onto larger square paper. They connect the mathematics activity to language arts as they talk about what they are thankful for, and to art as they make their designs. The lesson also has a real-life connection to the Thanksgiving holiday, as students put their pieces together to make a Thanksgiving quilt.

Now watch an extended video segment at left (duration 5:47) of the "Thanksgiving Quilts" video.

  Take a closer look at this activity