Triangles

=Concept Map= =Additional Resources=

OER

 * 1) List web resources with a brief description of what it contains; how it can be used and whether it can be by teacher/ student or both
 * 2) Books and journals
 * 3) Textbooks
 * 4) Syllabus documents

Non-OER
=Learning Objectives=
 * 1) List web resources with a brief description of what it contains; how it can be used and whether it can be by teacher/ student or both
 * 2) Books and journals
 * 3) Textbooks
 * 4) Syllabus documents

Concept #1. Formation of a triangle, elements of a triangle and its measures

 * 1) A	triangle is a three sided closed	figure.
 * 2) It	is one of the basic shapes in geometry.
 * 3) It triangle is	a	polygon with	three edges and	three	vertices.
 * 4) There	are three angles in a triangle formed at the three vertices of the	triangle.
 * 5) Interior	and exterior angles in a triangle at a vertex, together form a	linear pair.

Activity No # 1 : Formation of a triangle
Prior knowledge of point, lines, angles, parallel linesResources needed
 * Objectives
 * 1) Understand		formation of triangles
 * 2) Recognize		elements of triangle
 * 3) Introduce		concepts of exterior angle.
 * Pre-requisites
 * Resources needed
 * 1) Digital : Computer, geogebra application, projector.
 * 2) Non digital : Worksheet and pencil
 * 3) Geogebra files : 	“1.Introduction to a triangle.ggb”
 * How to do
 * 1) Use the geogebra file to illustrate.
 * 2) How many lines are there? Are the lines meeting?
 * 3) Are the two lines parallel? How can you say they are parallel or not?
 * 4) How many angles are formed at the point of intersection?
 * 5) What is the measure of the total angle at the point of intersection of two lines?
 * 6) Of the four angles formed which of the angles are equal? What are they called?
 * 7) Do the three intersecting lines enclose a space? How does it look? It is called a triangle.
 * 8) What are the points of intersection of these three lines called?
 * 9) The line segments forming the triangle are called sides.
 * 10) How many angles are formed when three lines intersect with each other?
 * 11) How many angles are enclosed by the triangle?
 * Evaluation at the end of the activity
 * 1) Can there be a closed figure with less than three sides?
 * 2) Can the vertices of the triangle be anywhere on a plane?
 * 3) What will happen if the three vertices are collinear?

Activity No # 2 : Elements of a Triangle
Prior knowledge of point, lines, angles, parallel lines Evaluation at the end of the activity
 * Objectives
 * 1) To understand the elements of a triangle
 * Pre-requisites
 * Resources needed
 * 1) Digital : Computer, geogebra application, projector.
 * 2) Non digital : Worksheet and pencil,6-8 strings (preferably in different colours)
 * 3) Geogebra files : 	“2. Elements of a triangle.ggb”
 * How to do
 * 1) Students work individually but in their groups.
 * 2) Take the strings and place them in such a way as to make a closed figure.
 * 3) What is the smallest number of strings with which you can form a closed figure?
 * 4) What is this figure called?
 * 5) Can you just draw the lines along the strings and see what you get?
 * 6) When you drew, what did you draw?  (Was it a line or was it an angle or was it a line segment?). It is a lime segment – how many line segments are there?
 * 7) When two line segments joined, what is it called?  (A vertex). How many vertices are there?
 * 8) Is there any angle formed when you made this figure? How many angles were formed?
 * 9) Show a simple Geogebra file with triangles – Use this file to demonstrate that every triangle has the elements - vertices, sides and angles
 * 10) How many triangles were formed?  Were there any strings left over?
 * 11) For each of the triangles trace the shape on the book and write down the elements of the triangle in the following format {| class="wikitable" !Vertices !Sides !Angles |- | | | |- | | | |- | | | |}
 * 12) For each of the triangles observe (inspect visually) which is the longest side and which is the shortest side {| class="wikitable" !Triangle name !Largest angle !Largest side !Smallest angle !Smallest side |- | | | | | |- | | | | | |- | | | | | |}
 * 13) Allow the students to explore if there is any connection between the two?
 * 14) After the students see the Geogebra file, they can attempt an alternative worksheet like below: {| class="wikitable" !Side 1 !Angle 1  (opposite angle) !Side 2 !Angle 2  (opposite angle) !Side 3 !Angle 3  (opposite angle) !Largest side and angle  ex-side1,angle1 !Smallest side and angle  ex-side3,angle3 |- | | | | | | | | |- | | | | | | | | |- | | | | | |}

1. Have the students been able to identify the elements in a triangle?

2. Have they been able to extrapolate any connection between the angle and side in a triangle?