Measuring Angles at the Treehouse Build

Read a protractor, check your measures, and draw angles for a backyard treehouse.

Read the protractor

Aunt Rosa and her helpers are building a treehouse. In each picture, the center of the protractor is on the vertex and one ray is on 0. Read the number where the other ray crosses the scale.

Aunt Rosa leans a ladder against the treehouse. What is the measure of the angle between the ladder and the ground?

The angle measures degrees.

Jamal measures the angle where a roof board meets the top of a wall. What is the measure of the angle?

The angle measures degrees.

Priya measures the angle between a corner brace and the floor. What is the measure of the angle?

The angle measures degrees.

Kenji's picture shows three rays. One ray is on 0. He wants the angle between the other two rays, so he counts from one of them to the other on the scale.

The angle between the two rays that are not on 0 measures degrees.

Check the measures

Careful builders check every measure. Use the pictures to decide which answers are right.

Before he measures, Jamal estimates the angle where the slide meets the platform. Which is the best estimate?

A. 20°B. 100°C. 160°D. 60°

Match each protractor to the measure of the angle it shows.

Hana needs a 55° angle for the rope swing's support board. Which protractor shows a 55° angle?

A. B. C. D.

Theo measures the angle where the railing meets a post. He says it measures 71° because the ray is one small mark past 70. Is Theo right?

A. Yes. The angle measures 71°.B. No. The ray is on the 80 mark, so the angle measures 80°.C. No. Each small mark stands for 5 degrees, so the angle measures 75°.D. No. He should read the scale from the left side, so the angle measures 105°.

Many protractors have two rows of numbers. Kai measures an acute angle on the treehouse window frame. The ray crosses both 40 and 140. Which measure is correct? Explain how you know.

Draw the angles

Use your protractor. Put its center mark on the endpoint of the ray and line up 0 with the ray that is drawn.

10.

Aunt Rosa needs a 40° angle for a shelf brace. Draw ray BA so that angle ABC measures 40°.

11.

The slide needs a 130° angle. Draw ray ED so that angle DEF measures 130°.