Why the Angles of a Triangle Add to 180 Worksheet Download
Free 6th Grade math worksheets on Why the Angles of a Triangle Add to 180. Each worksheet has 4 problems with an answer key and are ideal for teachers and homeschooling. You can download the PDF, create a set of flash cards or set it up for online learning.
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About this worksheet
Each worksheet has 4 problems showing the three corners of a triangle fitted together on a straight line.
Develop is the first word of this standard and nothing on the site does it. The other worksheets use the fact that a triangle totals 180 degrees; nowhere does a student see why it is 180 rather than some other number, and the argument is one they can do with scissors, which is the only reason to teach the fact at this grade rather than simply stating it. The same three angles are drawn twice, once as the corners of the triangle and once fitted together along a line, and they are generated once and used for both pictures so the two figures cannot drift apart. The straight line is built from rays on a half turn, so the three pieces really do fill 180 degrees rather than merely being drawn side by side. Sheets can be customized, turned into flash cards, or assigned for online learning.
Student objectives
- See that the three corners of a triangle fit along a straight line.
- Say that a straight line measures 180 degrees.
- Use the fact to find a missing angle.
Everyday practice
- Tear the corners off a paper triangle and line them up.
- Say what a straight angle measures.
- Explain why the total is the same for every triangle.