Illustrative Math Alignment: Grade 8 Unit 9

Putting It All Together

Lesson 2: Regular Tessellations

Use the following Media4Math resources with this Illustrative Math lesson.

Title	Body	Curriculum Topic
Math Example--Area and Perimeter--Circular Area and Circumference: Example 10	Math Example--Area and Perimeter--Circular Area and Circumference: Example 10 Topic Geometry Description This example presents a circle with radius x and a shaded sector with central angle θ (theta). The task is to express the area of the shaded sector in terms of x and θ. The solution involves using the central angle to find the fractional amount of the total area: A = (θ / 360) * π * x2 = πx2θ / 360.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 11	Math Example--Area and Perimeter--Circular Area and Circumference: Example 11 Topic Geometry Description This example presents a circle with radius x and a shaded sector with central angle θ (theta). The task is to express the arc length of the shaded region in terms of x and θ. The solution involves using the central angle to find the fractional amount of the circumference: Arc Length = (θ / 360) * (2 * π * x) = (θ * x / 180) * π.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 12	Math Example--Area and Perimeter--Circular Area and Circumference: Example 12 Topic Geometry Description This example features a circle with a radius of 5 units and a shaded sector with central angle θ (theta). The task is to express the area of the shaded sector in terms of θ. The solution involves using the central angle to find the fractional amount of the total area: Area = (θ / 360) * (π * 52) = 25π / 360 * θ = 5π / 72 * θ.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 13	Math Example--Area and Perimeter--Circular Area and Circumference: Example 13 Topic Geometry Description This example presents a circle with a radius of 5 units and a shaded sector with central angle θ (theta). The task is to express the arc length of the shaded region in terms of θ. The solution involves using the central angle to find the fractional amount of the circumference: Arc Length = (θ / 360) * (2 * π * 5) = θ / 18 * π.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 14	Math Example--Area and Perimeter--Circular Area and Circumference: Example 14 Topic Geometry Description This example features a circle with radius x and a shaded sector with a central angle of 30 degrees. The task is to express the area of the shaded sector in terms of x. The solution involves using the central angle to find the fractional amount of the total area: Area = (30 / 360) * (π * x2) = π * x2 / 12.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 15	Math Example--Area and Perimeter--Circular Area and Circumference: Example 15 Topic Geometry Description This example presents a circle with radius x and a shaded sector with a central angle of 30 degrees. The task is to express the arc length of the shaded region in terms of x. The solution involves using the central angle to find the fractional amount of the circumference: Arc Length = (30 / 360) * (2 * π * x) = x / 6 * π.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 16	Math Example--Area and Perimeter--Circular Area and Circumference: Example 16 Topic Geometry Description This example features two concentric circles with radii of 5 and 4 units, and a shaded sector with a central angle of 30 degrees. The task is to calculate the area of the shaded region. The solution involves using the central angle to determine the fractional area difference between the larger and smaller circles: Area = (θ / 360) * (π * r12 - π * r22) = (30 / 360) * (π * 52 - π * 42) = π / 12 * (25 - 16) = 3π / 4.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 17	Math Example--Area and Perimeter--Circular Area and Circumference: Example 17 Topic Geometry Description This example presents two concentric circles with radii of 5 and 4 units, and a shaded sector with a central angle of 30 degrees. The task is to calculate the perimeter of the shaded region. The solution involves calculating arc lengths based on the central angle and adding straight-line segments between radii: Perimeter = (θ / 360) * (2 * π * r1 + 2 * π * r2) + 2 * (r1 - r2) = (30 / 360) * (2π * 5 + 2π * 4) + 2 * (5 - 4) = 3π / 2 + 2.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 18	Math Example--Area and Perimeter--Circular Area and Circumference: Example 18 Topic Geometry Description This example features two concentric circles with radii x and y, and a shaded sector with a central angle θ (theta). The task is to express the area of the shaded region in terms of x, y, and θ. The solution uses the central angle to find the fractional area difference between the larger and smaller circles: Area = (θ / 360) * (π * x2 - π * y2) = (θπ / 360) * (x2 - y2).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 19	Math Example--Area and Perimeter--Circular Area and Circumference: Example 19 Topic Geometry Description This example presents two concentric circles with radii x and y, and a shaded sector with a central angle θ (theta). The task is to express the perimeter of the shaded region in terms of x, y, and θ. The solution involves calculating arc lengths based on the central angle and adding straight-line segments between radii: Perimeter = (θ / 360) * (2πx + 2πy) + 2(x - y) = π/180 * θ(x + y) + 2(x - y).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 2	Math Example--Area and Perimeter--Circular Area and Circumference: Example 2 Topic Geometry Description This example features a circle with a radius of 5 units. The objective is to calculate the circumference of the circle using the given radius. The solution involves applying the circumference formula: C = 2 * π * r = 2 * π * (5) = 10π. Circular area and circumference calculations are fundamental in geometry. These examples provide students with practical applications of theoretical concepts, helping them understand the relationship between a circle's radius and its circumference.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 20	Math Example--Area and Perimeter--Circular Area and Circumference: Example 20 Topic Geometry Description This example features two concentric circles with radii 5 and y, and a shaded sector with a central angle of 30 degrees. The task is to express the area of the shaded region in terms of y. The solution involves calculating the difference between the areas of the larger and smaller circles, accounting for the central angle: Area = π/12 * (25 - y2).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 21	Math Example--Area and Perimeter--Circular Area and Circumference: Example 21 Topic Geometry Description This example features two concentric circles with radii 5 and y, and a shaded sector with a central angle of 30 degrees. The task is to calculate the perimeter of the shaded region. Given a central angle of 30 degrees, radius 5, and unknown radius y, the perimeter is calculated as: Perimeter = π/6 * (5 + y) + 2(5 - y).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 22	Math Example--Area and Perimeter--Circular Area and Circumference: Example 22 Topic Geometry Description This example presents two concentric circles with radii 4 and x, and a shaded sector with a central angle θ (theta). The task is to express the area of the shaded region in terms of x and θ. The solution uses the central angle to find the fractional area difference between the larger and smaller circles: Area = (θ / 360) * (π * x2 - π * 42) = (θ * π / 360) * (x2 - 16).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 23	Math Example--Area and Perimeter--Circular Area and Circumference: Example 23 Topic Geometry Description This example features two concentric circles with radii x and 4, and a shaded sector with a central angle θ (theta). The task is to express the perimeter of the shaded region in terms of x and θ. The solution involves calculating arc lengths based on the central angle and adding straight-line segments between radii: Perimeter = (θ / 360) * (2 * π * x + 2 * π * 4) + 2 * (x - 4) = (π / 180) * θ(x + 4) + 2(x - 4).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 3	Math Example--Area and Perimeter--Circular Area and Circumference: Example 3 Topic Geometry Description This example introduces a circle with an unknown radius represented by x. The task is to express the area of the circle in terms of x. The solution demonstrates how to use the area formula with a variable radius: A = π * r2 = π * (x)2 = π * x2. Working with variable expressions in geometry helps students transition from concrete to abstract thinking. This example bridges the gap between numerical calculations and algebraic representations, a crucial skill in advanced mathematics.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 4	Math Example--Area and Perimeter--Circular Area and Circumference: Example 4 Topic Geometry Description This example presents a circle with an unknown radius represented by x. The task is to express the circumference of the circle in terms of x. The solution demonstrates how to use the circumference formula with a variable radius: C = 2 * π * r = 2 * π * x = 2πx. Understanding circular area and circumference is crucial in geometry. This example helps students transition from concrete numerical values to abstract algebraic expressions, fostering a deeper comprehension of the relationship between a circle's radius and its circumference.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 5	Math Example--Area and Perimeter--Circular Area and Circumference: Example 5 Topic Geometry Description This example features two concentric circles with radii of 5 and 4 units. The task is to calculate the area of the shaded region between these circles. The solution involves subtracting the area of the smaller circle from the area of the larger circle: A = π * (5)2 - π * (4)2 = 25π - 16π = 9π. Concentric circles and shaded regions introduce students to more complex geometric concepts. This example builds upon basic circular area calculations, encouraging students to think about the relationships between different circles and how to find areas of composite shapes.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 6	Math Example--Area and Perimeter--Circular Area and Circumference: Example 6 Topic Geometry Description This example presents two concentric circles with radii of 5 and y units. The objective is to express the area of the shaded region between these circles in terms of y. The solution involves subtracting the area of the smaller circle from the area of the larger circle: A = π * (5)2 - π * y2 = 25π - πy2 = π(25 - y2).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 7	Math Example--Area and Perimeter--Circular Area and Circumference: Example 7 Topic Geometry Description This example features two concentric circles with radii x and y. The task is to express the area of the shaded region between these circles in terms of x and y. The solution involves subtracting the area of the smaller circle from the area of the larger circle: A = π * x2 - π * y2 = π(x2 - y2).	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 8	Math Example--Area and Perimeter--Circular Area and Circumference: Example 8 Topic Geometry Description This example presents a circle with a radius of 5 units and a shaded sector with a central angle of 30 degrees. The task is to calculate the area of the shaded sector. The solution involves using the central angle to find the fractional amount of the total area: A = (30 / 360) * π * 52 = 25π / 12.	Area and Circumference
Math Example--Area and Perimeter--Circular Area and Circumference: Example 9	Math Example--Area and Perimeter--Circular Area and Circumference: Example 9 Topic Geometry Description This example features a circle with a radius of 5 units and a shaded arc corresponding to a central angle of 30 degrees. The task is to calculate the length of the shaded arc. The solution involves using the central angle to find the fractional amount of the circumference: Arc Length = (30 / 360) * 2 * π * 5 = 5π / 6.	Area and Circumference
Math Example--Geometric Transformation--Transformations: Example 1	Math Example--Geometric Transformation--Transformations: Example 1 Topic Transformations Description This example demonstrates a simple translation in geometric transformations. Two "T" shapes are shown on a grid, labeled "Before" and "After". The "Before" shape on the left is translated to become the "After" shape on the right, illustrating how an object can move position without changing its size or orientation.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 10	Math Example--Geometric Transformation--Transformations: Example 10 Topic Transformations Description This example showcases a combination of reflection and translation in geometric transformations. Two circular "O" shapes are displayed on a grid, one labeled "Before" and the other "After". A red dashed line indicates the axis of reflection. The transformation involves first reflecting the shape across this axis and then translating it to a new position. This demonstrates how multiple transformations can be applied in sequence to create more complex movements.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 11	Math Example--Geometric Transformation--Transformations: Example 11 Topic Transformations Description This example demonstrates a single rotation in geometric transformations. Two circular "O" shapes are shown on a grid, one labeled "Before" and the other "After". The shape undergoes a rotation around a point indicated by a pushpin, which serves as the axis of rotation. This illustrates how an object can change its orientation without altering its size or position relative to the rotation point.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 12	Math Example--Geometric Transformation--Transformations: Example 12 Topic Transformations Description This example illustrates a combination of rotation and reflection in geometric transformations. Two circular "O" shapes are displayed on a grid, one labeled "Before" and the other "After". The transformation involves two steps: first, a rotation around a point indicated by a pushpin, which serves as the axis of rotation, followed by a reflection across a red dashed line representing the axis of reflection. This demonstrates how multiple transformations can be applied sequentially to create more complex changes in orientation and position.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 13	Math Example--Geometric Transformation--Transformations: Example 13 Topic Transformations Description This example demonstrates a single reflection in geometric transformations. Two grids are shown with the letter "O" before and after a transformation. The "Before" grid has the "O" on the left side, while the "After" grid has it on the right side. A red dashed line indicates the axis of reflection in the middle of the two "O"s. Below, there is a diagram showing the reflection transformation along this axis, illustrating how the shape is flipped across the line while maintaining its size and shape.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 14	Math Example--Geometric Transformation--Transformations: Example 14 Topic Transformations Description This example illustrates a complex combination of transformations: translation, rotation, and reflection. Two grids are shown with an "O" shape before and after transformations. The "Before" grid has an "O" with a red dot at its center, while the "After" grid shows the same "O" but rotated and reflected. Below, a step-by-step diagram illustrates three sequential transformations: first, a translation moves the shape, then a rotation turns it around a pushpin (indicating the axis of rotation), and finally, a reflection flips it across a red dashed line.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 15	Math Example--Geometric Transformation--Transformations: Example 15 Topic Transformations Description This example demonstrates a simple translation in geometric transformations. Two grids are displayed with the letter "F" before and after a transformation. The "Before" grid shows an "F" on the left side, and the "After" grid shows it on the right side. Below, there is an arrow indicating that only a translation occurred between the two positions of the letter, showcasing how an object can move position without changing its size or orientation.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 16	Math Example--Geometric Transformation--Transformations: Example 16 Topic Transformations Description This example demonstrates a combination of translation and rotation in geometric transformations. Two grids are shown with the letter "F" before and after transformations. The "Before" grid has an upright "F", while the "After" grid shows it rotated 90 degrees clockwise. Below, there is a diagram illustrating two steps: first, a translation moves the shape, then a rotation turns it around a pushpin axis.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 17	Math Example--Geometric Transformation--Transformations: Example 17 Topic Transformations Description This example illustrates a combination of reflection and translation in geometric transformations. The image shows a large letter "F" on a grid transforming into a letter "L". The transformation involves two steps: first, a reflection across an axis represented by a red dashed line, and then a translation to a new position.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 18	Math Example--Geometric Transformation--Transformations: Example 18 Topic Transformations Description This example demonstrates a single rotation in geometric transformations. The image shows the letter "F" on a grid being rotated to form the same letter in a different orientation. A pushpin indicates the axis of rotation, and an arrow shows the direction of rotation, illustrating how an object can change its orientation without altering its size or shape.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 19	Math Example--Geometric Transformation--Transformations: Example 19 Topic Transformations Description This example illustrates a combination of rotation and reflection in geometric transformations. The image shows the letter "F" being transformed into an upside-down version of itself. This transformation involves two steps: first, a rotation around an axis indicated by a pushpin, followed by a reflection across a line represented by a red dashed line.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 2	Math Example--Geometric Transformation--Transformations: Example 2 Topic Transformations Description This example illustrates a combination of transformations: translation and rotation. Two "T" shapes are shown on a grid, labeled "Before" and "After". The shape undergoes a translation (movement) and a rotation, with a pushpin indicating the axis of rotation. This demonstrates how multiple transformations can be applied sequentially to a shape.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 20	Math Example--Geometric Transformation--Transformations: Example 20 Topic Transformations Description This example demonstrates a single reflection in geometric transformations. The image shows the letter "F" being reflected to form the letter "L". A red dashed line indicates the axis of reflection, illustrating how the letter changes its orientation through this single transformation. This showcases how an object can be flipped over a line while changing its shape and orientation.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 21	Math Example--Geometric Transformation--Transformations: Example 21 Topic Transformations Description This example demonstrates a complex combination of transformations: translation, rotation, and reflection. The image shows an uppercase letter "F" on a grid labeled "Before" and a transformed version of the letter "F" upside down on another grid labeled "After." Below, there are illustrations showing the three steps of the transformation process.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 22	Math Example--Geometric Transformation--Transformations: Example 22 Topic Transformations Description This example demonstrates a simple translation in geometric transformations. The image shows an uppercase letter "Z" on a grid labeled "Before" and a horizontally shifted version of the same letter on another grid labeled "After." Below, there is an illustration showing just a translation, indicating that the letter "Z" is moved horizontally without any rotation or reflection.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 23	Math Example--Geometric Transformation--Transformations: Example 23 Topic Transformations Description This example illustrates a combination of translation and rotation in geometric transformations. The image shows an uppercase letter "Z" on a grid labeled "Before" and an uppercase letter "N" on another grid labeled "After." Below, there are illustrations showing the two steps of the transformation: first a translation (moving the figure) followed by a rotation (turning the figure). A pushpin indicates the axis of rotation.	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 24	Math Example--Geometric Transformation--Transformations: Example 24 Topic Transformations Description This example demonstrates a combination of reflection and translation in geometric transformations. The image shows an uppercase letter "Z" on a grid labeled "Before" and a rotated and translated version of the same letter in another position on another grid labeled "After." Below, there are illustrations showing the two steps of the transformation: first, a reflection (flipping the figure across an axis shown by the red dashed line) and then a translation (moving the figure).	Definition of Transformations
Math Example--Geometric Transformation--Transformations: Example 25	Math Example--Geometric Transformation--Transformations: Example 25 Topic Transformations Description This example demonstrates a single rotation in geometric transformations. The image shows a transformation of the letter "Z" from an upright position to a rotated position resembling "N". The grid background helps visualize the transformation, and a pushpin icon indicates the axis of rotation, illustrating how an object can change its orientation without altering its size or shape.	Definition of Transformations

Illustrative Math Alignment: Grade 8 Unit 9

Putting It All Together

Lesson 2: Regular Tessellations

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