Angles for Kids | A fun and engaging intro into the world of angles for kids

Angles. There are lines everywhere. Straight lines that can go on forever. Line segments with two end points. And then there are rays that are lines used to form angles, having a single end point. Angles are formed by two rays that share a common end point. An angle measures the amount of turn. The common end point of an angle is called the vertex. There are many terms related to angles, which are necessary to learn as they are used to identify, compare, contrast, and measure angles. It is important to know and understand these terms. Angles are also found in other geometric shapes. Some figures include three angles, like the triangle. And some have many more, like the octagon, which has a total of eight angles. A square and a rectangle each have four angles. A pentagon has five angles, and a hexagon has six angles. All polygons have angles. One thing you may notice immediately is that angles come in different sizes. The size of an angle is measured using a unit called degrees. This is not the same as measuring temperatures. An angle can have any measurement from zero to 360 degrees. A complete circle is also 360 degrees. Notice the movement of the red ray inside this circle. Each movement increases the angle size. Measuring angles. How do you measure angles? With a protractor. A special tool is used to measure angles and degrees called a protractor. Protractors are easy to use as a ruler. Simply read the measurement shown to determine the degrees. Align the center of the protractor with the vertex of the angle. The red angle measures 60 degrees. The blue angle measures 130 degrees. The angle using the black line measures 90 degrees. If the angle is measured from right to left, use the bottom row of numbers. If it's measured from left to right, use the top row of numbers. Measuring angles is almost like measuring the length of a line. Once you practice measuring angles, it will be just as easy to. Notice, if two protractors were placed end to end, they would form a circle with a total measurement of 360 degrees. Types of angles. As you can see, angles come in all sizes. The different sizes of angles are identified based on the degree of measurement. There are five types of angles that you must be able to identify. This is how to remember them. An acute angle is less than 90 degrees. And that's a cute angle. What a cute angle. A right angle is exactly 90 degrees. It's just right. An obtuse angle is greater than 90 degrees, but less than 180 degrees. Obtuse sounds like obese or big. A straight angle is exactly 180 degrees. And it looks like a straight line. A reflex angle is greater than 180 degrees. Reflex, like flexing an arm. Angles need to be labeled like lines or line segments. There are a couple of methods used to measure angles. Here's some examples of angles and how they're labeled. This angle is labeled as angle BCD or angle DCB. Note, the vertex is in the middle. The same angle can also be called angle 1, as shown here. Both labels are correct. In this example, angle 2 can be labeled as angle BAD or angle DAB, or sometimes angle A. All labels are correct. When you label angles in a figure, try to use the same method for each of the angles. Otherwise, it could be confusing for the person trying to identify the names of each angle. Finally, there are two more terms used when identifying angles. They are used when you add the measures of two different angles. Complementary angles are two angles added together equaling 90 degrees. Supplementary angles are two angles added together equaling 180 degrees. Here are some examples. Can you recognize the difference between supplementary and complementary angles? Angle 1 equals 30 degrees and angle 2 equals 60 degrees. 30 degrees plus 60 degrees equals 90 degrees. So angle 1 is complementary to angle 2. Angle 3 equals 110 degrees and angle 4 equals 70 degrees. 70 degrees plus 110 degrees equals 180 degrees. So angle 3 is supplementary to angle 4. Drawing Angles Now that you know all about angles, it is time to draw your own angles using a protractor. Follow these instructions to draw a 50 degree angle. Note the center line on the protractor. Align it on a straight line. Any point will do. Find 50 degrees on the bottom row of numbers. Make a point. Make another point above the center line. Use the straight edge of a ruler or protractor and connect the points. Artists use angles for their work. They are also used by architects for buildings and homes. And engineers use them to design bridges. Everywhere you look, you will find angles including in picture frames, furniture, TVs, ceiling fans, windows, and they are also located in many many other places. Which angle best represents who you are and why? Acute, obtuse, straight, right, or reflex?