A proportion is an equation that states that two ratios are equal. In a proportion, the cross products of the ratios are equal. A proportion can be written in the form *a/b = c/d*, where a and d are the extremes, and b and c are the means.

Proportional relationships are relationships between two equal ratios. If two quantities are in a proportional relationship, their ratio always remains the same. For example, if you are traveling at a constant speed, the distance you travel is directly proportional to the time you travel. As time increases, the distance also increases in proportion.

Proportional reasoning involves using proportions to solve problems. This can be applied to various real-life situations, such as scaling drawings, solving problems involving similar figures, and calculating unit rates.

- Understand the concept of a ratio and how it relates to a proportion.
- Learn how to identify proportional relationships in tables, graphs, and word problems.
- Practice solving proportions using cross multiplication.
- Apply proportional reasoning to solve real-life problems, such as finding unit rates, scaling figures, and solving for unknown quantities in similar figures.
- Review different types of proportional relationships, including direct variation and indirect variation.

Remember to practice solving a variety of proportion problems to build your understanding and confidence in the topic.

.Study GuideSimilarity and scale Worksheet/Answer key

Similarity and scale Worksheet/Answer key

Similarity and scale Worksheet/Answer key

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Number and Operations (NCTM)

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

Understand and use ratios and proportions to represent quantitative relationships.

Compute fluently and make reasonable estimates.

Develop, analyze, and explain methods for solving problems involving proportions, such as scaling and finding equivalent ratios.

Geometry (NCTM)

Analyze characteristics and properties of two- and three-dimensional geometric shapes and develop mathematical arguments about geometric relationships.

Understand relationships among the angles, side lengths, perimeters, areas, and volumes of similar objects.

Create and critique inductive and deductive arguments concerning geometric ideas and relationships, such as congruence, similarity, and the Pythagorean relationship.

Apply transformations and use symmetry to analyze mathematical situations.

Describe sizes, positions, and orientations of shapes under informal transformations such as flips, turns, slides, and scaling.

Measurement (NCTM)

Apply appropriate techniques, tools, and formulas to determine measurements.

Solve problems involving scale factors, using ratio and proportion.

Grade 8 Curriculum Focal Points (NCTM)

Geometry and Measurement: Analyzing two- and three-dimensional space and figures by using distance and angle

Students use fundamental facts about distance and angles to describe and analyze figures and situations in two- and three-dimensional space and to solve problems, including those with multiple steps. They prove that particular configurations of lines give rise to similar triangles because of the congruent angles created when a transversal cuts parallel lines. Students apply this reasoning about similar triangles to solve a variety of problems, including those that ask them to find heights and distances. They use facts about the angles that are created when a transversal cuts parallel lines to explain why the sum of the measures of the angles in a triangle is 180 degrees, and they apply this fact about triangles to find unknown measures of angles. Students explain why the Pythagorean Theorem is valid by using a variety of methods - for example, by decomposing a square in two different ways. They apply the Pythagorean Theorem to find distances between points in the Cartesian coordinate plane to measure lengths and analyze polygons and polyhedra.