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4th grade math · Unit 8: Angles, perimeter, and area

Measuring with a protractor

What this lesson shows

Center on the vertex, baseline on one ray, read the scale that starts at 0.

The worked example

The lesson works this one step by step: 50°. Then your kid tries one like it on paper.

The steps

  1. Estimate first
  2. Center on the vertex
  3. Edge along a ray
  4. Read the row from 0

Helping at home

Draw one ray first, then put the protractor’s center on its end and the straight edge along it. Find the row of numbers that starts at 0 on that ray, count up to the angle, and make a dot there. Draw the second ray through the dot, and check: less than 90° is acute, more is obtuse.

If your kid gets stuck

Start from the 0 on your ray.

Watch it with Lux

With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.

See how Lux works

Standards

  • Common Core 4.MD.C.6
    Measure angles in whole-number degrees using a protractor. Sketch angles of specified measure.
Matches standards in 46 statesSee each state's code

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