1. Number Talk Pretend this is an array. _____ x _____ = ________
Be prepared to share your strategy.
Number Talk

2. Number Talk Pretend this is an array. _____ x _____ = ________
Be prepared to share your strategy.
Number Talk

3. Lesson 2-10 Classifying Triangles
Vocabulary: acute triangle, obtuse triangle, right triangle, equilateral triangle, isosceles triangle, properties, scalene triangle

4. Math Message On a quarter-sheet of paper, list everything you know about triangles. Be prepared to explain your list.

5. Math Message Follow-Up
A triangle is a 3-sided polygon.
A triangle has 3 vertices.
The lengths of a triangle’s sides can vary.
The angles in a triangle can be different sizes.
There are different types of triangles.

6. Identifying Different Triangles
What is an obtuse angle?
Show me with your arms.
What is an acute angle?
What is a right angle?

7. Today were are focusing on classifying triangles by angles.
Acute, Obtuse, and Right Triangles Equilateral, Isosceles, Scalene Triangles.
Look at the poster on our board.
An acute triangle is a triangle in which all angles are smaller than a right angle.
An obtuse triangle is a triangle in which one angle is larger than a right angle.
A right triangle is a triangle with one 90◦ angle.
Another way to classify triangles is by side lengths.
An equilateral triangle has all equal sides.
An isosceles triangle has at least two equal sides.
A scalene triangle has no equal sides
Today were are focusing on classifying triangles by angles.

8. Let’s practice with the geoboards and the rubber bands again to build different triangles.
Make a triangle with “one” obtuse angle.
What can we name this triangle?
Make a triangle with 3 acute angles.
Make a right triangle.
What can be name this triangle?
Make a triangle with “two” acute angles.

9. The right angle is the biggest angle in the triangle.
What are the properties or attributes of right triangles. You talk; I’ll record.
It has one right angle.
The right angle is the biggest angle in the triangle.
The side opposite the right angle is the longest side of the triangle.
The two line segments that intersect to form the right angle are perpendicular. Perpendicular line segments form a 90 degree angle.

10. Complete math journal page 57. (12 minutes)
To summarize, you will share the different properties you recorded.
(2 min)

11. Exit Ticket
Identify one of the triangles with only “one” type of angle.

12. If time permits, play “Rugs and Fences” in EM4 math games.