Perpendicular and parallel straight lines 2 2/2


Have your measuring tool and folded sheet from the previous lesson. Choose a sheet of origami paper.

An additional sheet should be given at the end of the lesson.


Question: What is special about the two pairs of sides of the square which have a common vertex?


Answer: Adjacent sides are perpendicular to each other and form a right angle.


Folding instructions:
Fold the shorter side as shown.

Check that the correct folding has been done not revealing the white side.


Folding instructions: Fold again the shorter side of your shape as shown.

The last two folding instructions must be checked carefully.


Folding instructions: Turn over your folded shape.

Check this folding instruction done by all the pupils.


Folding instructions: Join the two opposite sides to the line of symmetry as shown.


Folding insructions: Flatten your shape and then fold two triangles as shown.

All folding must be done on a flat surface.


Folding instructions: Fold the other two vertices as shown.

The size and exactness of the folds is not important.


Folding instructions: Turn over your shape.

Show your turned over shape to all of the pupils.


Folding instructions: The next folds are on the upper part of the shape.


Folding instructions: Fold the two vertices as shown.


Finally the dress!


A summing up question: What can be noticed with each pair of orange colored lines?


A summing up question: What can be noticed about the two lines shown in the animation? How can you check?



A summing up question: Can you find other pairs of perpendicular lines and pairs that are not perpendicular?


Answer 1:
A pair of non perperdicular lines can be seen as they do not form a right angle.


Answer 2:
A pair of intersecting lines that are not perpendicular can be seen.



Choose another sheet of origami paper.


Folding instructions: Make 4 folds on this new sheet in any way you choose.


Check how many pairs of intersecting lines are perpendicular to each other.


Activity: Draw a line which is parallel to the given red line. How can we check that this line is parallel to the red line?

If the slide with the red line is projected on a whiteboard pupils can be asked to draw a suitable line which is parallel to the red line and also another line which is perpendicular to the red line.
This activity can also be done in a workbook.


Activity: Draw a line which is perpendicular to the red line.
 Lesson Aims
During the folding process the pupils will identify parallel and perpendicular lines.
 Name of Model
A dress.
 The Lesson Structure
According to the curriculum.
 Lesson content
This is the second lesson on parallel and perpendicular lines following the prepatory lesson on parallel and perpendicular lines1 1/2. In this lesson will identify aparallel and perpendicular lines in other situations. The final model will be a surprise for the pupils and at the same time learning new concepts and revising previously learnt concepts.
 Prior Knowledge
The concepts of angle,straight angle and square.
 Materials
Origami sheets 15/15 cm, the measuring tool and two colored markers.