Ratio and Proportional Thinking Review

🔑 Key Concepts

  • Proportional relationships can be represented with tables, graphs, equations, and word problems.
  • The constant of proportionality is often found using \( k = \frac{y}{x} \).
  • Graphs of proportional relationships are straight lines that pass through the origin.
  • Unit rates can involve whole numbers, decimals, or fractions.
  • Equations such as \( y = kx \) show proportional relationships when \( k \) is constant.

✏️ Worked Examples

🧠 Math Vocabulary

  • Proportional relationship: a relationship where two quantities have a constant ratio.
  • Constant of proportionality: the constant value \( k \) in an equation like \( y = kx \).
  • Unit rate: a rate with a denominator of 1 unit.
  • Equivalent ratios: ratios that describe the same relationship.
  • Origin: the point \( (0,0) \), which proportional graphs must pass through.

💡 Main Idea

Ratio and proportional thinking problems can appear in many forms. Students may need to find a unit rate, identify a constant of proportionality, test whether a table or graph is proportional, or choose equations that correctly represent a relationship.

📚 What You Should Already Know

Students should know how to divide fractions, simplify ratios, read ordered pairs, interpret tables and graphs, and recognize that proportional relationships can be written in the form \( y = kx \).

🚀 What Comes Next

After reviewing ratio and proportional thinking, students can apply these skills to percent problems, slope, linear equations, scale drawings, similar figures, and real-world rate problems.

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