Exploring the Sum of Interior Angles in Triangles

In this video, Mr. Triangle and his friends, Mrs. Trapezoid and Mr. Rectangle, discuss the sum of their interior angles. While Mr. Rectangle and Mrs. Trapezoid know their angles sum to 360°, Mr. Triangle is unsure. Through exploration, they discover that the angles of any triangle always add up to 180°, regardless of its size or shape. This consistent rule is demonstrated and celebrated by the characters.

What is the sum of the interior angles of a rectangle?

• 180 degrees

• 90 degrees

• 360 degrees

• 270 degrees

What is the sum of the interior angles of a trapezoid?

• 360 degrees

• 180 degrees

• 270 degrees

• 90 degrees

What was Mr. Triangle unsure about?

• His name

• His shape

• His color

• The sum of his angles

What did Mr. Triangle and his friends discover about the sum of the angles in a triangle?

• They are always 180 degrees

• They are always 270 degrees

• They are always 90 degrees

• They are always 360 degrees

Tags

CCSS.8.G.A.5

How did Mr. Triangle feel after learning about his angles?

• Sad

• Confused

• Angry

• Excited

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CCSS.RL.6.3

CCSS.RL.6.6

CCSS.RL.7.6

CCSS.RL.8.6

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What happens when you tear apart any triangle and put it together?

• It forms a straight line

• It forms a square

• It forms a circle

• It forms a rectangle

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CCSS.1.G.A.2

Does the size or shape of the triangle affect the sum of its interior angles?

• Yes, it changes with both size and shape

• No, it remains 180 degrees

• Yes, it changes with shape

• Yes, it changes with size

Tags

CCSS.8.G.A.5

Who confirmed the rule about the sum of the angles in a triangle?

• Mr. Rectangle

• Mrs. Trapezoid

• Kevin

• Mr. Triangle

Tags

CCSS.8.G.A.5