This document provides a lesson plan on classifying triangles by their angles and side lengths. It begins with activating prior knowledge of angle types and having students draw and define acute, obtuse, right and straight angles. It then defines and provides examples of acute, obtuse, right, scalene, isosceles and equilateral triangles. Students are asked to classify sample triangles and solve problems identifying triangle types. The document concludes with a partner activity to create and classify triangles.

1. AIM: Classify Triangles
Do Now
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2. Pages 532-533 #6-10 all, 13, 14, 22, 23
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3. Who was Euclid?
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4. Anticipatory Set:
Write the definition of each type of angle and then draw each type of angle.
Acute Angle Right Angle Obtuse Angle Straight Angle
Definition
Drawing
1.) Draw an additional line segment that will change the acute,
obtuse, and right angles into triangles.
2.) Why can the straight angle not be changed into a triangle if
you drew only one additional line segment?
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5. Classifying Triangles by Angle Measures
1.) Acute Triangle: A triangle where all angles are acute.
2.) Obtuse Triangle: A triangle that has one obtuse angle.
3.) Right Triangle: A triangle that has one right angle.
Classifying Triangles by Side Lengths
4.) Scalene Triangle: A triangle that has no congruent sides.
5.) Isosceles Triangle: A triangle that has at least two
congruent sides.
6.) Equilateral Triangle: A triangle that where all of the sides
are congruent.
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6. THINK-PAIR-SHARE
Classify each triangle according to its sides and angles.
a.) b.)
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7. 1 Indentify the triangle
below.
A Equilateral Triangle
B Isosceles Acute Triangle
C Isosceles Right Triangle
D Isosceles Obtuse Triangle
E Scalene Acute Triangle
F Scalene Right Triangle
G Scalene Obtuse Triangle
1 2
4 3
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8. 2
A
B
C
D
E
F
G
1 2
4 3
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9. 3
A
B
C
D
E
F
G
1 2
4 3
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10. 4
A
B
C
D
E
F
G
1 2
4 3
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11. 5
A
B
C
D
E
F
G
1 2
4 3
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12. 6
A
B
C
D
E
F
G
1 2
4 3
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13. 7
A
B
C
D
E
F
G
1 2
4 3
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14. 8
A
B
C
D
E
F
G
1 2
4 3
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15. 9
A
B
C
D
E
F
G
1 2
4 3
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16. BEFORE YOU LEAVE: Trade-a-Triangle
1.) Create a triangle with your partner.
2.) Exchange the example with the other partnership in your
group and classify their triangle by the sides and angles.
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17. Mr. Tjersland's Math 7
Homework: Pages 376-377 #1-3 all, 5-7 all, 9-11 all, 15-17 all,
24, 25, 32-36 all
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18. AIM: Classify Triangles
10 Indentify the triangle
below.
A Equilateral Triangle
B Isosceles Acute Triangle
C Isosceles Right Triangle
D Isosceles Obtuse Triangle
E Scalene Acute Triangle
F Scalene Right Triangle
G Scalene Obtuse Triangle
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