Post on 17-Jan-2016
Learning Objective
Students will identify attributes of triangles.
skill concept context
Prior Knowledge
On your whiteboard, draw the shape of this sign.
This shape is a triangle. Triangles come in different shapes. Today you are going to learn some new names for triangles.
triangle
Prior Knowledge
Whiteboard:Draw two differentthree-sided figures.
Share Out:Hold up your whiteboard.Look around the room to see what your classmates
have drawn.
triangle
Examples of Triangles
Triangle means “three sides”
Any three-sided shape is a trianglebut only if each of the three sides are
straight.
Non-Examples of Triangles
These are not triangles because they do not have three sides.
Why is it important to know about different triangles?
Triangles are used in buildings and bridges.
Concept Development Definition
All triangles have special names
based on the length of their sides.
Special Triangles have special names
Let’s learn about what makes these triangles special…
isosceles
equilateral
scalene
Equilateral Triangle
All triangles have special names based on the length of their sides.
A triangle thathas three sides of equal length.
4 cm4 cm
4 cm
6 cm6 cm
6 cm
Isosceles Triangle
All triangles have special names based on the length of their sides.
A triangle thathas two sides of equal length.
7 cm
4 cm
7 cm
9 cm
9 cm
5 cm
Scalene Triangle
All triangles have special names based on the length of their sides.
A triangle thathas no sides of equal length.
3 cm
5 cm
8 cm
6 cm
9 cm
4 cm
Concept Development Definition
All triangles have special names based on the length of their sides.
Guided Practice #1
Pair share: Why does the triangle have this special name?
Whiteboard: What is the special name for this triangle?
has three sides of equal length.
All triangles have special names based on the length of their sides.
6 cm6 cm
6 cmAn equilateral triangle
Guided Practice #2
Pair share: Why does the triangle have this special name?
Whiteboard: What is the special name for this triangle?
has two sides of equal length.
All triangles have special names based on the length of their sides.
7 cm
4 cm
7 cm
An isosceles triangle
Guided Practice #3
Pair share: Why does the triangle have this special name?
Whiteboard: What is the special name for this triangle?
A scalene triangle has no sides of equal length.
All triangles have special names based on the length of their sides.
3 cm
5 cm
8 cm
What is our Definition?
All triangles have special names based on the length of their sides.
Time for
Independent Practice
What Did We Learn
Students will identify triangles by their attributes.
1. Are all triangles the same?2. What is the name of a triangle with 3
sides that are the same length?3. What is the name of the triangle with 2
sides that are the same length?4. What is the name of a triangle with no
sides that are the same length?