Common Core Math Grade 4 Fraction Addition and Subtraction

One goal of the Common Core is to develop a deeper understanding of fractions by using a progression of concepts from simple to complex. This lesson prepares students for the conceptual shift involved in progressing from adding and subtracting whole numbers to adding and subtracting fractions. Students are guided to think of operations with fractions as very much like operations with whole numbers.
Students see that you can count with unit fractions just as you count with whole numbers. And because you can count with unit fractions, you can also do arithmetic with them. If you walked 2/5 of a mile (2 fifths) yesterday and 4/5 of a mile (4 fifths) today, altogether you walked 6/5 of a mile (6 fifths; because 2 things plus 4 more of those things is 6 of those things).
Students use the meaning of fractions and the meanings of addition and subtraction that were built in earlier grades to understand why the procedures for adding and subtracting fractions make sense.
Aligned with Common Core standard 4.NF.B.3a/b