🔑 Key Concepts
- A ratio compares two quantities.
- A part-to-part ratio compares one part of a group to another part of the same group.
- The order matters. If the question asks for mako sharks to hammerheads, count mako sharks first.
- Ratios can be simplified by dividing both numbers by their greatest common factor.
- Ratio language helps explain the comparison, such as “3 mako sharks for every 4 hammerheads.”
✏️ Worked Examples
🧠 Math Vocabulary
- Ratio: a comparison of two quantities.
- Part-to-part ratio: a ratio comparing one part of a group to another part of the same group.
- Simplest form: a ratio written so both numbers have no common factor other than 1.
- Greatest common factor: the largest factor shared by two numbers.
- For every: ratio language used to explain how two quantities compare.
💡 Main Idea
To write a ratio from a picture, count each group carefully, place the numbers in the order asked by the question, and simplify if possible. Ratio language such as “for every” helps students understand what the simplified ratio means and how the same comparison can scale up to larger quantities.
📚 What You Should Already Know
Students should know how to count objects in a picture, identify the order of a ratio, find common factors, divide both parts of a ratio by the same number, and explain comparisons using “for every” language.
🚀 What Comes Next
After writing simple ratios from pictures, students can create equivalent ratios, solve ratio word problems, complete ratio tables, and connect ratio language to unit rates and proportional relationships.
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