Teaching Ratios and Bar Graphs
Creative Curricula Using Elementary Recipe Math Lesson Plan
Mar 21, 2008
Kids love to concoct. Use this juicy lesson to teach students about ratios. Then report data using a bar graph.
Teaching Ratios with Secret Recipes
Content Areas: ratios, measurement, data collection, graphing
Materials: flour, baking powder, salt, shortening, milk, mixing bowl, measuring spoons, a measuring cup, large spoon, 3X5 index cards, bottles of 100% juices (classroom management tip: ask each child to bring in one bottle of any flavor), several bottles of plain seltzer water, large paper cups, small measuring cups (one per group - 1/8 cup size would work best), paper towels , blindfolds, poster board, markers
As a Class:
Use humor to introduce the idea of ratios as they pertain to recipes. Ask students what ingredients you would need if you wanted to make biscuits. Write those ingredients on the board. Undoubtedly, students will spend some time negotiating the ingredients. Once you feel like you have them "hooked," cross out all but the necessary ingredients, adding any that they might have missed:
- flour
- baking powder
- salt, shortening
- milk
Now ask students to jot down the ingredients biscuit recipe on a recipe card. Is knowing the ingredients enough? Ask five individual students to help you put the recipe together (class management tip: for drama and interest, provide a silly apron and/or chef's hat for each student). While one student stirs the ingredients in a large mixing bowl, ask each of the other students to choose a random measured amount of each ingredient. Does it look like the recipe might work? Why or why not? Obviously, students needed to know the measured amounts in order to make the recipe.
Introduce the term "ratio" to your students: A ratio is a statement of how two numbers or measurements compare in size. Explain that you could show a relationship like one part milk to two parts flour three different ways:
- With a colon ~ 1:2
- With words~ 1 to 2
- With a fraction ~ 1/3 (Classroom management tip: Challenge students to explain why the fraction is 1/3 rather than 1/2; If students need extra help, draw a measuring cup on the board and divide it into thirds to show how 1 part + 2 parts = 3 parts, or thirds)
Create a Bar Graph
Small Group Activity (groups of three):
- Provide each group with three different types of juice, a small measuring cup, a cup for each student in the group, and as many additional cups as there are additional groups to hold aside. For instance, if there are five groups, each group would have four extra cups set aside.
- Provide groups with five minutes to come up with their own "secret bubbly juice recipe" in which they use ratios ("parts") . (Example: 1 part orange, 2 parts mango, 1/2 part seltzer). Tell students that the recipe must fit into a cup. When they have agreed on a recipe, allow students to create and taste their group recipe (in their own cups) and to give their drink a try before creating additional "taste test" recipes in the extra cups.
- Ask one person from each group to come up for a "blind taste test." Ask each tester to choose his or her favorite two flavors.
- On the posterboard create the basis for a bar graph with recipe names along the X-axis and ordinal numbers along the Y-axis.
- Allow tasters to color in a bar for each of their favorite juice recipes.
- Use ratios to discuss the bar graph (Example: Students preferred "Grape Razzler" to "Funny Fruits" in a ratio of 2:1)
Follow up by including group recipes in a class newspaper.
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