This Application Problem is a part of the Lesson 10, Unit 4, Grade 4. Seeking to construct a straight angle, some students may place two triangles or trapezoids side by side, leaving gaps between the angle sides. Encourage them to verify 180° by adding the interior angles of the pattern blocks. Ask, "What shape could fit in this gap? How can you confirm that you've made a straight angle?" Using pattern blocks of the same shape or different shapes, construct a straight angle.