Lines and angles : Lines and angles Lesson objective:
To be able:
to draw lines and angles
to estimate the size of angles
to identify types of angle. [Level 4/5] Key words:
parallel
perpendicular
right
acute
obtuse Starter:
Sketch a pair of
parallel lines
Perpendicular lines
Slide 2: Parallel lines – NEVER meet Random lines – Intersect at a point X Perpendicular lines – Intersect at right angles Draw the following lines and write down some names for them. X
Slide 3: What is ANGLE ??? An angle is formed when two lines meet and is measured in degrees. We use a little circle ° following the number to mean degrees. For example 32° means 32 degrees. 32 °
Slide 4: What is the size and the name of this angle? 90° - Right angle
Slide 5: What is the size and the name of this angle? 180° - Half turn
Slide 6: What is the size and the name of this angle? 360° - Full turn
Slide 7: 90° - Right angle 180° - Half turn 360° - Full turn IMPORTANT ANGLES TO REMEMBER
Slide 8: What is the size and the name of this angle? Less than 90° - Acute angle
Slide 9: All the angles which are less than 90° are ACUTE ANGLES
Slide 10: What is the size and the name of this angle? Between 90° and 180°- Obtuse angle
Slide 11: All the angles which are between 90° and 180° are OBTUSE ANGLES
Slide 12: What is the size and the name of this angle? Between 180° and 360°- Reflex angle
Slide 13: All the angles which are between 180° and 360° are REFLEX ANGLES
Slide 14: Summary Acute Angle: less than 90°
Obtuse Angle: more than 90° but less than 180°
Reflex Angle: more than 180° but less than 360°
Slide 15: AB = AC OR AB = CD and AD = BC AB is parallel to CD or AB//CD AD is parallel to BC or AD//BC EXAMPLE
Slide 16: Write down which of the angles below are acute, which are obtuse and which are reflex. Estimate the size of each one. Work in pairs….
Slide 17: a. BC = DE = CD b. BC = DE c. BC = CD Work in pairs…. d. BD = CE
Slide 18: Identify any type of angles Obtuse angles Right
angles Work in pairs….
Slide 19: Identify any type of angles Obtuse
angle Obtuse
angles Right
angles Acute
angles Work in pairs….
Slide 20: http://mathspool2.co.uk/#/grade-c-2011/4544717033 PLENARY Easy angles => Type of angles
Slide 21: The protractor helps us to measure the size of an angle. Later on we learn how to use it.
Slide 22: http://www.mathplayground.com/alienangles.html
Estimate angles-NOT for this lesson