Line segments, rays, and angles Literature Link: Young Math: Angles are Easy as Pie by Robert Froman Line segments, rays, and angles Lesson 16-2 CCSS 4.G.1

MATH Essential Questions How can lines, angles, and shapes be described, analyzed, and classified? MATH Essential Questions

How are angles measured? MATH Essential Questions

Warm up A carton of eggs has 12 eggs. Greg used 1/3 of his carton of eggs to make breakfast. Trisha used ¼ of her carton of eggs for breakfast. Who used more eggs, Greg or Trisha? Explain.

Today’s Lesson In this lesson, you will identify and name line segments, rays, and angles. Let’s look at the Envision Video for this lesson and take the quiz.

Line segments - Vocabulary A line segment is a part of a line with two endpoints. Segments do not go on forever like lines do. Line segments are named by the letters on their two endpoints. J K

MORE Vocabulary Ray: A type of line that begins at a point and goes on forever in one direction. Angle: Two rays that meet at the same endpoint Vertex: The point where 2 rays meet (and form an angle).

Use pipe cleaners to make a right angle. Right Angles Right Angle: An angle that makes a square corner. I would have students practice making right angles with their pipe cleaners. Use pipe cleaners to make a right angle.

Use pipe cleaners to make an acute angle. Acute Angles Acute angle: An angle that is open less than a right angle (with its rays closer together). You can remember that an acute angle’s opening is littler than a right angle because it is “a cute little angle”. Have students practice making acute angles with their pipe cleaners and notice that acute angles can be varying sizes. Use pipe cleaners to make an acute angle.

Use pipe cleaners to make an obtuse angle. Obtuse Angles Obtuse angle: An angle that has an opening bigger than a right angle (with its rays farther apart). Memory Trick! An obtuse angle is big, and obtuse sounds like obese (which means big). It’s an obtuse obese angle! Have students practice making obtuse angles with their pipe cleaners. Use pipe cleaners to make an obtuse angle.

Practice! Draw an acute angle in your notebook. Draw a right angle in your notebook. Draw an obtuse angle in your notebook.

Name that Angle!

Think and write Think of a clock. Give an example of a time that the clock’s hands make a right angle. Give an example of a time the clock’s hands make an obtuse angle, and a time the clock’s hands make an acute angle.

With a partner, complete the activity “Making Roads.” Moving Around town With a partner, complete the activity “Making Roads.”

Lesson Wrap Up In this lesson, you learned that line segments and rays can help describe parts of lines and geometric shapes. You also learned angles are formed by two intersecting lines and classified by size. Homework (16-2 Practice) for one “Paw Signature” and (16-2 Reteaching & Practice) if you want two “Paw Signatures.” Website for Practice: http://www.sheppardsoftware.com/mathgames/geometry/shape shoot/line_shoot.htm