2D shapes lesson slides

1. 2D shapes

2. Recap...

3. Polygon Song
• http://youtu.be/69lfTURDles?t=18s

4. Angles investigation – 5 minutes
• Draw a triangle
• Measure the three angles
• Rip out the triangle’s corners with the angles
• Draw a straight line
• Do the angles fit on the straight line?
• What does that tell you about the angles?
• Draw another triangle and check whether it
works everytime!

8. Circle degrees

9. 1 triangle has angles that add upto
180degrees
what about 3 triangles?
1
3
2
What is the
sum of angles
in a pentagon?

10. Fill the ‘angles’ column in table
• Fin the angles side for the shapes as much as
you can by attempting to segment them into
triangles.
• Work in pairs to check with each other.

11. On your own...
• Investigate whether
– A square is a rectangle OR
– A rectangle is a square
• Then discuss with the person next to you and
come up with a convincing argument to present to
the class.

12. Identical Halves
• Work in pairs!
• You have been given 2 shapes
• Cut out the shapes
• Fold it in half so both sides are on top of each
other exactly
• How many different ways can it be done?
• Can anyone remember what it’s called?
• Repeat the procedure for other shapes
• Continue to fill in your table as you go along.

13. Parallel Lines
Perpendicular lines

14. Blue lines are parallel because they never meet
and are always the same distance apart
Red and blue lines are perpendicular to each other because they
form a right angle (90degrees)

15. NEXT LESSON - Types of Triangles
• Symmetry lines investigation
– When does a triangle have
• Three lines of symmetry - Equilateral
• One line of symmetry - Isosceles
• No line of symmetry - Scalene

16. Bingo!
• I gives clues to describe the shape and you have
to guess the correct shape and cross it off your
bingo grid.
• I will use the following:
– Number of equal/unequal sides
– Angles
– Lines of symmetry
– Number of edges
– Types of lines – parallel and perpendicular

17. Exciting shapes

18. Exciting shapes
- Angles
- Sides
- Parallel lines?
- Equal sides?

19. Fill your tables in as far as you can