Octagon

An octagon is a polygon with eight sides and eight angles. The name "octagon" is derived from the Greek words "octa," meaning eight, and "gonia," meaning angle.

Properties of an Octagon:

Number of sides: An octagon has 8 sides.
Number of angles: An octagon has 8 angles.
Sum of interior angles: The sum of the interior angles of an octagon is 1080 degrees.
Sum of exterior angles: The sum of the exterior angles of an octagon is 360 degrees.
Regular vs. Irregular: An octagon can be regular (all sides and angles are equal) or irregular (sides and/or angles are not equal).

How to Identify an Octagon:

To identify an octagon, look for a shape with eight straight sides and eight angles. Each angle should measure 135 degrees in a regular octagon. In an irregular octagon, the sides and angles may vary in length and measure.

Examples of Octagon Shapes:

Here are some examples of objects or shapes that resemble an octagon:

Stop signs
Some sports arenas and courts
Certain architectural elements, such as windows or rooms

Study Guide:

Here are some key points to remember when studying octagons:

Identify the number of sides and angles in an octagon.
Understand the properties of the interior and exterior angles of an octagon.
Practice identifying and drawing octagon shapes.
Learn to differentiate between regular and irregular octagons.

Understanding the properties and characteristics of octagons can help in geometry and spatial reasoning tasks, as well as in everyday observations of shapes in the environment.

◂Math Worksheets and Study Guides First Grade. Place Value

Vocabulary/Answer key

Place Value

Vocabulary/Answer key

Place Value

The resources above cover the following skills:

Number and Operations (NCTM)

Understand numbers, ways of representing numbers, relationships among numbers, and number systems.

Use multiple models to develop initial understandings of place value and the base-ten number system.

Develop a sense of whole numbers and represent and use them in flexible ways, including relating, composing, and decomposing numbers.

Connect number words and numerals to the quantities they represent, using various physical models and representations.

Grade 1 Curriculum Focal Points (NCTM)

Number and Operations: Developing an understanding of whole number relationships, including grouping in tens and ones

Children compare and order whole numbers (at least to 100) to develop an understanding of and solve problems involving the relative sizes of these numbers. They think of whole numbers between 10 and 100 in terms of groups of tens and ones (especially recognizing the numbers 11 to 19 as 1 group of ten and particular numbers of ones). They understand the sequential order of the counting numbers and their relative magnitudes and represent numbers on a number line.