Mrs. Hafen’s fourth-graders are working all the angles as they learn to use a protractor and discover the properties of angles.

Fourth-Grade Core Standards include:

Standard 4.MD.5 Recognize angles as geometric figures that are formed wherever two rays share a common endpoint, and understand concepts of angle measurement.

Understand that an angle is measured with reference to a circle with its center at the common endpoint of the rays, by considering the fraction of the circular arc between the points where the two rays intersect the circle. An angle that turns through 1/360 of a circle is called a “one-degree angle,” and can be used to measure other angles.

Understand that an angle that turns through n one-degree angles is said to have an angle measure of n degrees.

Standard 4.MD.6 Measure angles in whole-number degrees using a protractor. Sketch angles of specified measure.

Standard 4.MD.7 Recognize angle measure as additive.

Understand that when an angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the angle measures of the parts.

Solve addition and subtraction problems to find unknown angles on a diagram in real-world and mathematical problems, for example by using an equation with a symbol for the unknown angle measure.

Strand: GEOMETRY (4.G.) Draw and identify lines and angles, as well as classify shapes by properties of their lines and angles (Standards 4.G.1–3)