This Instructional Activity is a part of the Lesson 2, Unit 9, Grade 8. The goal of this activity is to study some types of pentagons that do tessellate the plane. Students make use of structure when they relate the pentagons in this activity to the hexagonal tessellation of the plane, which they have seen earlier. All triangles and all quadrilaterals give tessellations of the plane. For the quadrilaterals, this was complicated and depended on the fact that the sum of the angles in a quadrilateral is 360 degrees. Regular pentagons that do not tessellate the plane have been seen in earlier activities.