How tall IS that?!

Heights seem to capture our imagination. Thanks to this week’s Bonus Challenge, the next time your student asks, “How tall IS that?!” you will be able to whip out a clinometer and respond, “Let’s find out!”

“Clinometer.” Fancy Nancy would use this word to refer to the protractor measuring thing your kids are going to use this week. You may have also heard the word, “theodolite,” which is a related tool that serves the same purpose. These instruments may sound a bit intimidating, but the process used to employ them is fairly simple. This website breaks it down into easy-to-follow steps. Still waiting for your clinometer to arrive in the mail? Click here for a downloadable version.

protractor measuring

Protractor 101

Here are a few fun facts about protractors:

  • Basic protractors were first used in Europe in the 13th century. No one is sure who actually invented them.
  • A U.S. naval captain named Joseph Huddart invented a more complex protractor in 1801, which was used to plot a ship’s position on a navigational chart.
  • Most protractors measure angles in degrees, but some measure them in radians. Many protractors have both systems of measuring on them.
  • Marine navigators use a “course protractor,” which allows them to measure the angular distance between magnetic north and their plotted course.
  • Thomas Jefferson was a big fan of the protractor. One of his personal protractors, made of brass, is on display at the Monticello Visitor’s Center.

Can you think of creative ways to use your protractor? If so, let us know about it! Email pics to

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