Difference between revisions of "Triangles"
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# Allow the students to explore if there is any connection between the two? | # Allow the students to explore if there is any connection between the two? | ||
− | # After the students see the Geogebra file, they can attempt an alternative worksheet like below: {| class="wikitable" !Side1 !Angle 1 (opposite angle) !Side2 !Angle 2 (opposite angle !Side3 !Angle 3 (opposite angle) !Largest side and angle ex-side1,angle1 !Smallest side and angle ex-side3,angle3 |- | | | | | | | | |- | | | | | | | |} | + | # After the students see the Geogebra file, they can attempt an alternative worksheet like below: |
+ | {| class="wikitable" | ||
+ | <small>|- | ||
+ | ! Header text !! Header text !! Header text !! Header text !! Header text !! Header text !! Header text !! Header text | ||
+ | |- | ||
+ | | Example || Example || Example || Example || Example || Example || Example || Example | ||
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+ | | Example || Example || Example || Example || Example || Example || Example || Example | ||
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+ | | Example || Example || Example || Example || Example || Example || Example || Example | ||
+ | </small>|} | ||
+ | {| class="wikitable" !Side1 !Angle 1 (opposite angle) !Side2 !Angle 2 (opposite angle !Side3 !Angle 3 (opposite angle) !Largest side and angle ex-side1,angle1 !Smallest side and angle ex-side3,angle3 |- | | | | | | | | |- | | | | | | | |} | ||
'''Evaluation at the end of the activity''' | '''Evaluation at the end of the activity''' |
Revision as of 11:11, 1 February 2019
Concept Map
Additional Resources
OER
- Web resources:
- Bright Hub Education - Basic concepts of triangles,Types of triangles,Angle sum property,Exterior and interior angle relation
- Folioz - Inequalities in triangle, Investigate the relationship between the sides and angles in a triangle
- JsunilTutorial - Test papers for triangles
- Books and journals
- Textbooks
- NCERT Textbooks – Class 9
- Karnataka Govt Text book – Class 8
- Syllabus documents
Non-OER
- Web resources:
CPALMS -Introduction to triangles as a closed three sided figure,Inequalities in triangles
- Books and journals
- Textbooks
- Syllabus documents (CBSE, ICSE, IGCSE etc)
Learning Objectives
- Identify a triangle
- Recognize interior and exterior angles
- Classifying types of triangles
- Recognize the angle sum property
- Establish relation between interior and exterior angles
Teaching Outlines
Concept #1. Formation of a triangle, elements of a triangle and its measures
- A triangle is a three sided closed figure.
- It is one of the basic shapes in geometry.
- It triangle is a polygon with three edges and three vertices.
- There are three angles in a triangle formed at the three vertices of the triangle.
- Interior and exterior angles in a triangle at a vertex, together form a linear pair.
Activity No # 1 : Formation of a triangle
- Objectives
- Understand formation of triangles
- Recognize elements of triangle
- Introduce concepts of exterior angle.
- Pre-requisites
Prior knowledge of point, lines, angles, parallel linesResources needed
- Resources needed
- Digital : Computer, geogebra application, projector.
- Non digital : Worksheet and pencil
- Geogebra files : “1.Introduction to a triangle.ggb”
- How to do
- Use the geogebra file to illustrate.
- How many lines are there? Are the lines meeting?
- Are the two lines parallel? How can you say they are parallel or not?
- How many angles are formed at the point of intersection?
- What is the measure of the total angle at the point of intersection of two lines?
- Of the four angles formed which of the angles are equal? What are they called?
- Do the three intersecting lines enclose a space? How does it look? It is called a triangle.
- What are the points of intersection of these three lines called?
- The line segments forming the triangle are called sides.
- How many angles are formed when three lines intersect with each other?
- How many angles are enclosed by the triangle?
- Evaluation at the end of the activity
- Can there be a closed figure with less than three sides?
- Can the vertices of the triangle be anywhere on a plane?
- What will happen if the three vertices are collinear?
Activity No # 2 : Elements of a Triangle
- Objectives
- To understand the elements of a triangle
- Pre-requisites
Prior knowledge of point, lines, angles, parallel lines
- Resources needed
- Digital : Computer, geogebra application, projector.
- Non digital : Worksheet and pencil,6-8 strings (preferably in different colours)
- Geogebra files : “2. Elements of a triangle.ggb”
- How to do
- Students work individually but in their groups.
- Take the strings and place them in such a way as to make a closed figure.
- What is the smallest number of strings with which you can form a closed figure?
- What is this figure called?
- Can you just draw the lines along the strings and see what you get?
- 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?
- When two line segments joined, what is it called? (A vertex). How many vertices are there?
- Is there any angle formed when you made this figure? How many angles were formed?
- Show a simple Geogebra file with triangles – Use this file to demonstrate that every triangle has the elements - vertices, sides and angles
- How many triangles were formed? Were there any strings left over?
- For each of the triangles trace the shape on the book and write down the elements of the triangle in the following format
Vertices | Sides | Angles |
---|---|---|
- For each of the triangles observe (inspect visually) which is the longest side and which is the shortest side
Triangle name | Largest angle | Largest side | Smallest angle | Smallest side |
---|---|---|---|---|
- Allow the students to explore if there is any connection between the two?
- After the students see the Geogebra file, they can attempt an alternative worksheet like below:
Header text | Header text | Header text | Header text | Header text | Header text | Header text | Header text | |
---|---|---|---|---|---|---|---|---|
Example | Example | Example | Example | Example | Example | Example | Example | |
Example | Example | Example | Example | Example | Example | Example | Example | |
Example | Example | Example | Example | Example | Example | Example | Example
|} Evaluation at the end of the activity 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?Activity No # 3 : Measures associated in a triangle
Prior knowledge of point, lines, angles, parallel lines
Evaluation:
Activity No # 4 : Interior and Exterior angles in a triangle
Prior knowledge of point, lines, angles
Note the measure of angles
| |