Angles for Kids: Acute, Right and Obtuse Angles (Grade 4 Math)

Hi, I'm Luna from DoodleBeez. Today we are learning about angles. An angle is made when two straight lines meet at a point. Some angles are sharp and narrow, and some are wide open.

Every angle has a corner point called the vertex, and two arms that stretch out from it. The size of an angle is how far it turns between the arms, and we measure it in degrees.

A right angle is a square corner, exactly ninety degrees. You can find right angles in the corners of a book, a door or a window. We mark a right angle with a little square.

An acute angle is smaller than a right angle, so it is less than ninety degrees. It looks sharp and narrow, like the pointy tip of a slice of pizza.

An obtuse angle is bigger than a right angle, but smaller than a straight line. That means it is between ninety and one hundred eighty degrees. It looks wide open, like the back of a deck chair leaning far back.

To sort any angle, compare it to a square corner. Smaller than the corner? It is acute. Exactly the corner? It is a right angle. Bigger than the corner, but not a straight line? It is obtuse.

Now it's your turn. Look at the clock hands at four o'clock. Is the angle acute, right or obtuse? Pause and try. Each number is thirty degrees apart, so four numbers make one hundred twenty degrees. It is obtuse.

Great job! Remember, a right angle is a square corner of ninety degrees. Acute angles are smaller than that, and obtuse angles are bigger. Practice angles in the Math Lab at doodlebeez.com. See you next time!