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Grade 4 Math · World 9: Angle and Shape Studio · Level 87
What Is an Angle?
Two rays sharing an endpoint: right, acute, or obtuse.
Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.
What children learn in Level 87
- An angle is two rays that share an endpoint. The shared endpoint is the vertex.
- A right angle is a square corner, like the corner of a page. A little square marks it.
- An acute angle is smaller than a right angle. An obtuse angle is bigger than a right angle.
Georgia's K-12 Mathematics Standards:
- 4.GSR.7.1 — Recognize angles as geometric shapes formed when two rays share a common endpoint. Draw right, acute, and obtuse angles based on the relationship of the angle measure to 90 degrees.
- 4.GSR.8.1 — Explore, investigate, and draw points, lines, line segments, rays, angles (right, acute, obtuse), perpendicular lines, parallel lines, and lines of symmetry. Identify these in two-dimensional figures.