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Brainsladder

Sketch Angles of a Specified Measure

Students draw angles of a given degree measure using a protractor. Students draw one ray, place the protractor correctly, mark the specified degree measure, and draw the second ray through that mark to create the angle.

How it is taught

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An angle is drawn from a vertex with two rays.

The protractor scale tells how wide the opening is.

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Read it: Read from the ray on 0

Put the center on the vertex and one ray along the base line. That ray is on the inner scale's 0, so the inner numbers count the turn: the other ray is at 70, and the angle is 70°.

  1. Put the center of the protractor on the vertex.
  2. Line one ray up with the base line, on a 0.
  3. Read from the 0 on that ray to the other ray: 70°.

Each scale counts the turn from its own 0, one from the right and one from the left.

The angle starts at the ray on 0, so only that scale counts this angle.

An angle narrower than a square corner is less than 90°, which checks the reading.

Read the numbers that start at 0 on one of the angle's rays. To make an angle, draw the ray at the mark.

Reading the other scale, and saying 110° for this angle.

110 counts from the other side's 0. The angle is narrower than a square corner, so it is 70°, less than 90°.

To make an angle of 140°, ray A lies on 0 of the inner scale. Which mark does ray C open to? — 140 on the inner scale. Count on the scale whose 0 is on ray A. 140 on the outer scale would make 40°.

Draw a 60° angle

Today we'll draw an angle that measures exactly sixty degrees.

First, draw one straight ray. The endpoint is called the vertex.

Now place a protractor so its center sits right on the vertex.

Line up the zero mark with our ray.

Count up the protractor scale: ten, twenty, thirty, all the way to sixty.

Make a small dot right at the sixty-degree line.

Lift the protractor. Draw a second ray from the vertex through your dot.

Look — the two rays meet at the vertex, opening sixty degrees apart.

Grade 4 · Using a protractor to draw an angle

That's a sixty-degree angle. Nice work!

Now you try. Open the second ray to the named measure. Open the ray to 75 degrees.

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics
Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal
1 star — one skill mastered, every rung of its ladder climbed
Climbing now
Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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