LESSON PLANNING OF USE PROTRACTOR TO CONSTRUCT ANGLES OF DIFFERENT MEASURES
Students` Learning Outcomes
- Use protractor to construct, right angle, straight angler and reflex angles of different measures
Information for Teachers
- A protractor is a tool, typically made of transparent plastic, for measuring angles. Protractor is used to measure angles in degrees (0) in geometry lessons in schools.
- The circle outside an angle`s arms is termed as Exterior Angle.
- The exterior angle of an obtuse angle or acute angle is known as Reflex Angle.
- A Reflex Angle is one which is more than 1800 but less than 3600
- Consult text book at all steps where and when required.
Material / Resources
Writing board, chalk / marker, duster, geometry box, textbook
- Ask students if they have seen sun rise or sun set?
- Draw a straight line on board and make half sun and ask how it looks at this time [show sample to the students].
- Tell them to open their geometry box and see if there is something resembling that.
- Let them explore that the shape of protractor resembles a half sun.
- Ask them to DRAW SUNRISE by using protractor, the way you drew on the board. [Show sample]
- Let them try, later helping them to draw on the board with the help of a protractor.
- Ask them to read and find total number of degrees on this D- shaped tool.
- May be they will answer 1800 or something else.
- Tell them that this is also an angle called straight angle.
- Tell the students that there are 1800 degrees in a straight angle. Ask students if they have ever heard the phrase “does a one-eighty”. It means to do things in opposite direction.
- Let them try to join two protractors in a way to complete a whole circle and then ask then count number of degrees it has.
- Let them explore that there are 3600 degree in a circle.
- Recall the concepts of angles which they have already studied in Grade 4
- Conduct one or two activities from previous grade if you find necessary.
- This will help to create a link.
- Make angle 4 of 1800by the hands of the clock; make the figure then change 4 directions.
- Encourage students to get ready for the game: Do as I do?
- Attempt following steps on board and ask students to do the same individually.
- Place the center of protractor at a point A which is point O.
- Look for the number 1800on protractor and mark a point on the paper next to 1800
- Take away the protractor and label the point C.
- Join point A and new point C by using ruler.
- Relate the clock hands and angles that 12 0` Clock is a Zero degree angle and 6 0` Clock is 1800angle. [Change the direction of Minute and Hour hand to form new angle]
Sum up / Conclusion
- Ask students what they have learnt during the period about the angles.
- Student will answer that angle of 1800 is called straight angle.
- Reflex Angle is one which is more than 1800 but less than 3600
- Reflex angle is larger angle, whereas its smaller angle may be acute or obtuse.
- Give angles of different degrees to the students and ask them to draw them and identify its type.
- Ask students to look for examples that show straight and reflex angles in their surroundings.
- Added 1800 in the noted angle that would be the required reflex angle, For example 450+ 1800 = 2250
- Reflex angle will be 1800