Polygon activity 3 decomposition and composition 1/2

Each student chooses two differently-colored squares from the fan and prepares their paper measurement tool.

Questions for Discussion:
What is the name of the paper polygon you have taken?
Can you describe it?

Answer:
The paper is square.  All the sides are the same length and all the angles are right angles.

Folding Instruction:
Fold one corner to lie on top of the non-adjacent corner (opposite corner).  Repeat with the other square.

Question for Discussion:
After the folding, what is the name of the polygon you have made?
Can you describe it?

Answer:
We have a triangle.  The polygon has three vertices and three sides.

Question:
What kind of triangle is it?

Answer:
The triangle has two sides of equal length so it is an isosceles triangle.  One corner is a right angle, so the triangle is a ‘right angled isosceles triangle’.

Question for Discussion:
How many different polygons can you make by putting together the two triangles, so that two sides of the same length will always touch?

Answer:
Two triangles will make:

• A parallelogram
  – A square
  – A big triangle

Question for Discussion:
How many different polygons can you by putting together THREE triangles, so that two sides of the same length will always touch?

Answer:
Three triangles will make:

– A trapezium
– A right-angled trapezium
– Two pentagons

Question for Discussion:
How many different polygons can you make by putting together FOUR triangles, so that two sides of the same length will always touch?

Answer:
– A trapezium
– A square
– A rectangle
– A parallelogram
– A big triangle
– A hexagon

Question for Discussion:
In which ways are these three polygons similar?

Question for Discussion:
In which ways are these three polygons different?

Question for Discussion:
In which ways are these two polygons similar?

Question for Discussion:
In which ways are these two polygons different?

Folding Instruction:
Take one of your folded triangles and make two more folds as you want.

Folding Instruction:
Open the paper and with your paper ruler (straight edge), go over the lines with a marker pen.

Question for Discussion:
Look at the polygons in the paper.  Write inside each polygon the name of the polygon.

This was a preparatory lesson for the next lesson, called ‘Polygons’.