Fractions and Rational Number Arithmetic

The most obvious appearance of math in the kitchen is in scaling recipes up or down, such as doubling (or halving) a recipe for 12 cookies to make 24 (or 6) cookies. This everyday task requires many mathematical skills and understandings, including:

• recognizing equivalent representations for the same number and generate them by decomposing and composing numbers;
• developing understanding of fractions as parts of unit wholes, as parts of a collection, as locations on number lines, and as divisions of whole numbers;
• recognizing and generating equivalent forms of commonly used fractions, decimals, and percents;

• using visual models, benchmarks, and equivalent forms to add and subtract commonly used fractions and decimals;
• selecting appropriate methods and tools for computing with whole numbers from among mental computation, estimation, calculators, and paper and pencil according to the context and nature of the computation and use the selected method or tools.

• developing and analyzing algorithms for computing with fractions, decimals, and integers and develop fluency in their use;
• developing and using strategies to estimate the results of rational-number computations and judge the reasonableness of the results;
• developing, analyzing, and explaining methods for solving problems involving proportions, such as scaling and finding equivalent ratios.

Food, such as cookies, sushi rolls, or your favorite recipe, presents a helpful and tasty path to understanding fractions beyond the finding equivalent fractions and adding that is used in scaling a recipe.