U.S. National Standards
N.1. Number and Operations
1.1. Understand numbers, ways of representing numbers, relationships among numbers, and number systems.
1.1.3. Develop understanding of fractions as parts of unit wholes, as parts of a collection, as locations on number lines, and as divisions of whole numbers.
1.3. Compute fluently and make reasonable estimates.
1.3.5. Use visual models, benchmarks, and equivalent forms to add and subtract commonly used fractions and decimals.
2.3. Use mathematical models to represent and understand quantitative relationships.
2.3.1. Model problem situations with objects and use representations such as graphs, tables, and equations to draw conclusions.