Angle sum property of a quadrilateral

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Showing the sum of angles of a quadrilaterals by placing the angles of the quadrilateral adjacent to each other with a hand on activity.

Objectives

To understand sum of angles of a quadrilateral is 360°

40 minutes.

Prerequisites/Instructions, prior preparations, if any

1. The students should have the knowledge of constructing quadrilaterals.
2. They should have the skill of drawing and measuring angles.

Materials/ Resources needed

colour papers, scale , compass, pencil and scissors.

This activity has been taken from the website :http://mathematicsvillage.blogspot.in/search/label/Activity

Process (How to do the activity)

1. Draw a Quadrilateral ABCD on colour chart Sheet .
2. Cut such four Quadrilaterals on four different sheets.
3. Mark <A as <1 , <B as <2 , <C as <3 and <D as <4 on each quadrilateral as shown in fig .
4. Arrange all four angles of quadrilateral one from each colour at one point.
5. What you observe ?
6. It forms a complete angle i.e 360 degrees.
7. This shows that sum of all angles of quadrilateral is 360 degrees.
• Developmental Questions:
1. What is a quadrilateral ?
2. How many angles does a quadrilateral have ?
3. What is the sum of 4 angles of the quadrilateral according to your findings.
• Evaluation:
1. What would be the sum of opposite angles of a quadrilateral ?
• Question Corner:
1. What can you say about the four angles in a regular quadrilateral ? Give an example for regular quadrilateral.
2. Try proving this property in case of concave quadrilaterals as well.