Goals: To use ratios to understand the relationship between different numbers
Time Required: 40 minutes, plus research time
Materials: "A Recipe for Ratios" student reproducible, drawing supplies, red/white paint, six paper cups, paint stirrer, and dry erase board and markers. Try these creative supplies from Sanford:
- Mr. Sketch® Watercolor Markers
- Prismacolor® Nupastel® Pastel Color Sticks
- Sharpie® Permanent Markers
- Paper Mate® Flair® Marker PensTM/MC
- Prismacolor® Premier Markers
- Paper Mate® Retractable Colored Pens
- FoohyTM Colored Pencils
- uni-ball® Vision EliteTM/MC Rollerball Colored Pens
- Expo® Dry Erase Markers
- Paper Mate® Mirado® Cedar Pencils
Background Discussion:
1. Ask students to answer the following questions by a show of hands. Record the answers as a ratio (e.g., 3:30, 5:30; 30:30).
- Who has a sibling?
- Who is wearing green?
- Who takes the bus?
- Who has braces?
- Who ate breakfast today?
2. Use these questions and answers to refresh students' understanding of ratios (a comparison of two numbers).
3. Take out a tube of red paint and a tube of white paint and place six paper cups on a table. Conduct the following experiment in front of the class, asking students to keep track of the ratio of white to red paint.
- Cup 1: one drop of white, one drop of red (1:1)
- Cup 2: one drop of white, three drops of red (1:3)
- Cup 3: one drop of white, six drops of red (1:6)
- Cup 4: three drops of white, one drop of red (3:1)
- Cup 5: six drops of white, two drops of red (6:2)
- Cup 6: two drops of white, two drops of red (2:2)
4. Ask:
- What is the difference between Cup 1 and Cup 6? (They are the same color, but there is double the volume. The same is true for Cup 4 and Cup 5.)
- How does this show how ratios might be helpful in the "real" world? (Ratios allow people to increase or decrease volume without changing the end result.)
5. Discuss how ratios could be helpful when cooking (increasing or decreasing the number of people that a recipe will serve). On the board, complete the following cooking-based ratio problem:
- A recipe for spice cookies calls for 4 cups of flour and 1 cup of sugar. What is the ratio of these two ingredients? (4:1.)
- If you were tripling this recipe, what would the new ratio be? (12:3.)
- The same recipe calls for 1½ teaspoons of cinnamon, 1 teaspoon of ginger, ½ teaspoon of nutmeg, and ¼ teaspoon of allspice. What is the ratio for these ingredients? (1.5:1:0.5:0.25.)
- If you were halving this recipe, what would the new ratio be? (0.75:0.5:0.25:0.125.)
Using the Student Reproducible:
6. Explain to students that they are going to put their understanding of ratios to the test by creating a class cookbook.
7.As a group, choose a cookbook theme such as graduation, class picnic, or Flag Day. It can be seasonal, based on a special occasion, or even themed around a book or country you have studied recently.
8.Instruct each student to choose two recipes that match the theme: one appetizer, dessert, or drink; and one main dish (NOTE: www.foodtv.com, www.cooking.com, and home cookbooks are useful recipe resources).
9. Distribute a copy of the "Recipe for Ratios" student reproducible. Instruct the students to rewrite their recipes so that there will be enough food for 30 to 40 students. (NOTE: Remind students that they must turn in copies of their original recipes.)
10. Each recipe card should be decorated to match the theme and include a drawing of what the final dish should look like. Later, make copies and bind them all together in a cookbook for each student to take home!
Challenge!
Ask students to trade recipes with a friend and rewrite them again, but this time for a small party of only four to six people.
A Recipe for Ratios
Student Name:
Write your recipe for 30 people in the space below. Decorate it based on your class's theme and be sure to include a drawing of what the final food should look like!
Recipe Name:
From the Kitchen of:
Serves 30
Ingredients:
What to Do:
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