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# A Look Into 4th Grade Geometry

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• 1. A Look Into 4th Grade Geometry
By: Bev Netusil
• 2. Geometry Topics
• What You Will Accomplish This Unit
By the end of this unit you will be able to;
Name and create shapes
Label Parts of shapes (i.e. Radius of a circle, base of a triangle)
Name different triangles.
Understand 3-Dimensional objects
How you can use polygons to create 3-D objects
Name and create 3-dimensional objects
Let’s Get Started!!!
• 13. 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.
• 14. Leg or Side: these are the lines that connect the vertices. There are always three sides on a triangle
• 15. Base: this is the bottom of the triangle.
• 16. 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
• 17. Squares
Rectangles
Shapes Con’t
I have 2 sets of equal sides
All my sides are equal
It is important to recognize the differences between squares and rectangles.
• 18. Circles
Shapes Con’t
This 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.
• 19. Radius: this is the distance from the centre point to any point on the circumference.
• 20. Diameter: this is the entire distance from one side of the circle to the other. The diameter is twice the distance of the radius.
• 21. 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
• 22. Can you name and recognize different polygons?
Naming and Recognizing Polygons
Am I a simple or complex polygon?
What’s my name?
What’s my name, and what kind of polygon am I?
• 23. To name a polygon you must be able to count the number of sides it has.
• 3 sides – triangle
• 24. 4 sides – quadrilateral
• 25. 5 sides – pentagon
• 26. 6 sides – hexagon
• 27. 7 sides – heptagon
• 28. 8 sides – octagon
• 29. 10 sides - decagon
Are these the only polygons? No!Polygons can have an infinite number of sides. Can you name them all?
Naming Polygons
I 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?
• 30. 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.
• 31. 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.
• 32. Q&A Con’t
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!
YES
NO
• 33. 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
NO
YES
• 34. 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
• 35. 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
• 36. 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 ANDdepth.
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.
• 37. 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
• 38. Has 6 square sides. Ex. Box
*Remember all sides must be equal!
• Has 6 rectangular sides. Ex. Fridge
• 39. 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
Cone
Cube
Rectangular Prism
• 40. 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,
• 41. Types of Prisms
Try to use your knowledge of polygons to identify these prisms...
Do you recognize this prism?
It’s a cylinder!
This is a pentagonal prism
This is a triangular prism
*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.
• 42. Geometry Activities
Shapes
• Have students identify and name shapes. What You Will Need: worksheet with different examples of shapes.
• 43. Quiz:
Name the 4 parts of a triangle.
What is the difference between a square and a rectangle?
Draw a circle and label the center, radius, diameter, and circumference.
• Have students draw and label different shapes
• Geometry Activities Con’t
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.
• 44. Have students produce polygons and create a design using each polygon to create a new school flag.
http://www.aaamath.com/g4_318x1.htm
http://www.aaamath.com/g4_318x2.htm
• 45. Geometry Activities Con’t
3-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/
• 46. Here’s Some Extra Bonus Help!