Key Concepts: Students recognize that when the angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the measure of the parts.
Generalization: Students will be able to solve addition and subtraction problems to find unknown angles on a diagram in real world and mathematical problems, e.g., by using an equation with a symbol for the unknown angle measures.
Backgrounds: This is a differentiated lesson plan in which the content has been previously explored. Students should know how to successfully measure angles with a protractor, and recognize measure angles as additives. At this point (4th grade) students should have a solid foundation on how to partition shapes into parts with equal areas…; (3.G.A.2). which will help them when they decompose pattern blocks into parts. They must also know how to recognize angles as geometric shapes that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement; (4.MD.C.5). They must also know that a circle is 360° and when split in half is 180°, as well as the meaning and measurements of vertex, and obtuse, acute, and right angles.