Access Point #: MAFS.912.G-CO.4.AP.12bArchived Access Point

Essential Understandings

Concrete:

• When given an angle, use manipulatives (e.g., compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, tracing paper, patty paper, etc.) to create another angle of equal degrees or measure.
  
  
• Draw a reference line with your straightedge. Place a starting point on the reference line.
• Place the point of the compass on the vertex of (point A).
• Stretch the compass to any length so long as it stays ON the angle.
• Swing an arc with the pencil that crosses both sides of .
• Without changing the span of the compass, place the compass point on the starting point of the reference line and swing an arc that will intersect the reference line and go above the reference line. (Click Here)
• Go back to and measure the width (span) of the arc from where it crosses one side of the angle to where it crosses the other side of the angle.
• With this width, place the compass point on the reference line where the new arc crosses the reference line and mark off this width on the new arc.
• Connect this new intersection point to the starting point on the reference line.

• Understand the following concepts and vocabulary: angle, reference line, straightedge, arc, intersection point, rays, compass and vertex.
• A shape formed by two lines or rays diverging from a common point..

º Formally: An angle is formed by the intersection of two rays with a common endpoint...
º Informally: When two segments (or lines or rays) intersect, they form an angle..

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