A Look Into 4th Grade Geometry

A Look Into 4th Grade Geometry

By: Bev Netusil

Geometry Topics Shapeso Triangleso Squareso Rectangleso Circles

Polygonso Triangleso Quadrilateralso Pentagono Hexagon

3-Dimensional Shapes

What You Will Accomplish This Unit

By the end of this unit you will be able to;

I. Name and create shapesII. Label Parts of shapes (i.e. Radius of a

circle, base of a triangle)III. Name different triangles.IV. Understand 3-Dimensional objectsV. How you can use polygons to create 3-D

objectsVI. Name and create 3-dimensional objects Let’s

Get Started!!!

Triangles

Shapes

This diagram shows four main components of a triangle;

• Vertex/Vertices: these are the points of the triangle. A triangle will always have three vertices.

• Leg or Side: these are the lines that connect the vertices. There are always three sides on a triangle

• Base: this is the bottom of the triangle.

• Angles: these help you determine which type of triangle it is; equilateral, isosceles, or scalene.

Can You Classify Triangles?This is an equilateral triangle. All of its sides

are equal. It is also an acute triangle because all its angles are less than 90o

This is a right-angle triangle

because it has a 90o angle

This is an isosceles

triangle because two of its

sides are the same.

This is an obtuse triangle because

one of its angles is larger than 90o

Squares Rectangles

Shapes Con’t

It is important to recognize the differences between squares and rectangles.

I have 2 sets of equal sides

All my sides are equal

Circles

Shapes Con’tThis diagram shows four major components of a circle;

• Centre: this is the centre of the circle, and the distance from this point to any point on the circumference is the same.

• Radius: this is the distance from the centre point to any point on the circumference.

• Diameter: this is the entire distance from one side of the circle to the other. The diameter is twice the distance of the radius.

• Circumference: this is the distance around the entire circle.

 A polygon is;

A plane shape (two-dimensional) with straight sides that must connect.

In a simple polygon none of the sides overlap. In a complex polygon the sides overlap.

(Note: a circle is not a polygon because it has a curved side)

Polygons

Can you name and recognize different polygons?

Naming and Recognizing Polygons

What’s my name?

Am I a simple or complex polygon?

What’s my name, and what kind of

polygon am I?

To name a polygon you must be able to count the number of sides it has. • 3 sides – triangle• 4 sides – quadrilateral• 5 sides – pentagon• 6 sides – hexagon• 7 sides – heptagon• 8 sides – octagon• 10 sides - decagon

Are these the only polygons? No! Polygons can have an infinite number of sides. Can you name them all?

Naming PolygonsI have 6 sides, therefore, I must be a hexagon!

I have 10 sides, therefore, I must be a decagon!

BONUS* The shapes above are known as simple polygons. Do you remember what a complex polygon looks like?

We are complex polygons! Did you remember how we looked?

How do you know these are complex polygons?

The easiest way to know if a polygon is complex is to ask yourself one simple question;

Do any of the lines cross?

- Yes. Then this polygon is a complex polygon.

- No. Then this is not a complex polygon. It would be known as a simple polygon.

I’m not sure how to recognize what is and what is not a polygon.

If you are not sure if it is a polygon there are simple questions you can ask yourself to

identify them.

Is This A Polygon? Q&A.

1. Is it on a plane? Or is it 2-Dimensional? In other words if you laid it in front of you would it lay flat?

If the answer is yes then you can move on to the next question!

Q&A Con’t

YES

NO

2. Do all the sides connect? In other words are there no holes within the shape?

If the answer is yes then you can move on to the next question!

Q&A Con’t

YES NO

3. Does it have three or more sides?

If you answer yes again then this shape is a polygon! That’s all! 3 Simple questions and now you can identify a

polygon!

Q&A Con’t

NO YES NO

What is a 3-Dimensional, or 3-D, object?

• It is an object that exists in three dimensions.

Now you ask, what does that even mean??

3-Dimensional Objects

So a 3-Dimensional object exists in three dimensions. Well that definition is not very helpful. What is three dimensions?

Well a 3-Dimensional object has depth. Refer back to polygons.

These objects had a width and a length. 3-D objects will have width,

length AND depth.

Use a box as an example!

*See how this box has a length, width and depth.

* A 3-D object will never lie flat. If you place it on a desk it will stand out from the desk.

Now that we know what 3-D objects are let’s try to name them!

3-Dimensional Objects Name (*Note: these are only some 3-D bjects)

Sphere

Cube

Rectangular Prism

Cone

Definitions

-Perfectly round. Ex. Ball

- Has 6 square sides. Ex. Box*Remember all sides must be equal!

-Has 6 rectangular sides. Ex. Fridge

- Has a circle base that extends up to a point. Ex. Ice Crem Cone

Can You Match The 3-D Objects To Their Name?

Sphere

Cube

Rectangular Prism

Cone

What are Prisms?A prism is a polyhedron with two congruent and parallel faces.

Basically if you take two of the same polygons and connect them so that they are parallel you will get a prism.

Here is an example,

Types of PrismsTry to use your knowledge of

polygons to identify these prisms...

*BONUS: add ‘al’ to the end of polygon names plus ‘prism’ at the end

to name the types of prisms. There are two

exceptions and they are rectangular and

triangular prisms.

Do you recognize this prism?It’s a cylinder!

This is a pentagonal prismThis is a

triangular prism

Geometry ActivitiesShapes

Have students identify and name shapes. What You Will Need: worksheet with different examples of shapes.

Quiz: a) Name the 4 parts of a triangle.b) What is the difference between a square and a

rectangle?c) Draw a circle and label the center, radius,

diameter, and circumference.

Have students draw and label different shapes

Geometry Activities Con’t

http://www.aaamath.com/g4_318x1.htm http://www.aaamath

.com/g4_318x2.htm

Polygons

Have students identify and name polygons. What You Will Need: worksheet with different examples of polygons. Be sure to include examples that are not polygons.

Have students produce polygons and create a design using each polygon to create a new school flag.

Geometry Activities Con’t3-Dimensional Objects Have students cut out this model

and fold it into a cube! There are outlines like these all over the internet! Let your students explore which 3-D shapes they can make.

http://www.korthalsaltes.com/

Here’s Some Extra Bonus Help!

Get these books to help add to your geometry unit!!

Use this slideshow to aid your students with geometry shapes, polygons and 3-

Dimensional objects, or for your own teaching

reference!