Let us understand the properties of 2D shapes

__Construction of 2D
shapes__

__Let us understand the
properties of 2D shapes.__

** **

__Square__

** **

**Let us know: **A Square has four sides. All the four sides are equal.

Let us make a square by folding a
paper by following the given steps.

**Step 1:** Take a paper

**Step 2:** Fold the paper as shown
in the figure.

Shade the extra portion in the bottom with red colour. Red coloured portion will be rectangular in shape. Tear it off and keep it aside. Open up the triangle. What do you observe? You could see a square.

The crease in the middle of the square
is called the 'Diagonal of the square'.

You can note that the diagonal divides
the square into two trianlges.

__Try this__

Can you find the other
diagonal of the square by folding it the other way? If so how many diagonals
can you find for a square?.

**Teacher's note: **Teacher can guide the children to do this paper folding activity.

Observe the number of sides and corners
of a square.

So, a square has **four** sides, **four** corners
and **two** diagonals.

__Think __

Are all the sides of a
square equal

What about the
diagonals?

Are they equal?

__We know from square
shape__

we shall
summarize the properties of a square as follows

* Square has four sides.

* All the
four sides are equal.

* Square has
four corners.

* Square has
two diagonals.

* The two diagonals are equal.

** **

__Rectangle__

** **

**Step 1:** Take the rectangular
piece which was kept aside. Observe its sides.

**Let us know: **Opposite sides are equal

Fold the opposite sides of the
rectangle. What
do you observe? The sides coincide.

Now we get opposite sides equal. Hence
in a rectangle, opposite sides are equal.

Fold the opposite corners as we did in
the square. Observe the crease. It shows the diagonal of the rectangle.

**Let us know: **Diagonals are equal in
rectangle.

__We
know from rectangle shape__

The properties of a rectangle are as
follows

* Rectangle has four sides.

*
Two opposite sides are equal.

*
Rectangle has four corners.

*
Rectangle has two diagonals.

* Two diagonals are equal.

__Rectangle__

Fold the square along any of these
diagonals to form a triangle.

Observe the Sides and corners of the
rectangle.

A triangle has **three** sides and **three**
corners.

Cut the paper and make triangles of
different kind.

Observe the length of the sides of the triangle. length of the sides. Let the children explore the names of different sides of the triangles.

__Try
This____:__** **How many triangles can be made out of this square paper?

Fold the square along any
of diagonals to form a triangle.

**Let us know**

**Teacher’s note: **Facilitate the children
to explore the properties of shapes in various aspects.

__Circle__

** **

**Let us know: **Circle is a closed curve

Draw a circle using pencil and Bangle.

**Step 1:** Place a bangle on the
paper as shown in figure.

**Step 2:** Trace the outline of the
bangle with a curved line with the pencil until you reach the starting point,
we get a circle.

__Now,
we get a circle__

On observing the circle drawn we shall
write the properties of it as follows.

* Circle has no sides.

*
Circle has no corners.

*
Circle has a center point.

__Activity 1__

Write the names of few
objects in everyday use and mention their geometrical shapes. Example, table−
cuboid

cookies – Circle -
Cylinder

wheels of a bike −
Circle – Cylinder

ball – sphere

pencil - cylinder

clock faces − Circle

dinner plates − Circle

chess boards − Square

slices of pizza −
Triangle

chapter book covers −
Rectangle

cell phones – Rectangle
- cuboid

__ __

__Practice__

1) Triangle
has ** Three** corners.

2) Four
sides of a square are __Equal.__

3) Circle
has ** No** sides.

4) Rectangle
has ** Two** diagonals.

5) Opposite
sides of a rectangle are __Equal.__

6) Circle has ** One**
centre point.

** **

__Plane
Surface__

Surface of few objects like walls, floors
papers and top of a table are flat. Flat surfaces are otherwise called as plane
surfaces or planes. Cubes and cuboids have flat surfaces.

** **

__Curved
Surface__

Surfaces of few objects such as ball,
flowerwase, pot are curved. Cone, Cylinder and sphere have curved surfaces.

** **

__Activity 2__

Draw all the 2d shapes
in the given dot grid. One is done for you.

**A geoboard is a
mathematical manipulative board.**

Join the dots in the
grid using curved lines to make designs of your choice. one is done for you.

**Teacher’s note : **Teacher can lead the
children to make the shapes drawn by them in the dot grid by using rubber band
in the Geo board drawn by them in the dot grid

__Activity 3__

**We can see many things around us have straight lines and curved
lines.**

Draw any 5 shapes and put a tick in the given boxes to indicate the type of the lines found in them.

**Teacher’s note : **Teacher can discuss
about the types of lines found in objects in everyday use and enable the
children to draw them in above tabular column.

__ __

__Practice__

Put a tick mark in the
appropriate columns.

Tags : Geometry | Term 1 Chapter 1 | 3rd Maths , 3rd Maths : Term 1 Unit 1 : Geometry

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3rd Maths : Term 1 Unit 1 : Geometry : Construction of 2D shapes | Geometry | Term 1 Chapter 1 | 3rd Maths

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