Geometry and Spatial Sense, Grades 4 to 6 - EduGains

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Important benchmark angles include:
In the later junior grades, students begin using standard units and tools (e.g., protractors)
to measure and construct angles. They also use specific angle measures to construct various
polygons like quadrilaterals and triangles.
MEASURING ANGLES
When students have had experiences identifying, comparing, and informally measuring
angles using benchmarks, they can begin to measure angles with units and tools such as
protractors. Standard protractors can be very confusing for junior students. There are no
visible angles on the protractor. The unit markings representing angles on the protractor are
very small and appear only on the edge. Most protractors contain two sets of numbers that
run in both directions.
Students need experiences with more “informal” protractors containing larger unit angles
to develop an understanding of how a protractor is used, and they can construct these
informal protractors themselves. For example, they can fold a piece of waxed paper to make
a transparent protractor.
This transparent protractor can be placed over angles or polygons, and students can see how
to measure the smaller angles in those figures by fitting them within the larger unit angles
of the waxed-paper protractor.
Straight angle Right angle Half of a right
angle (45°)
Waxed paper 1st fold 2nd fold 3rd fold 4th fold Cut and unfold
In this case the smaller angles could be referred to as wedges, and the angle above would
measure approximately three and a half wedges.
Geometry and Spatial Sense, Grades 4 to 6