"Common Core Standard 5.NF.1 Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators."

How to add fractions:

If the denominators are the same simply add the numerators, but don't add the denominators. For example: 2⁄4+ 1⁄4= 3⁄4

Step 3. Add the numerators but do not add the denominators

In this example we created a mixed number by dividing 17 by 12 which gives you the mixed number 1 5/12 however, you don't have to simplfy into a mixed number.