Adding fractions with unlike denominators can be cloudy, but attaching the fractions to real-life math can add to fraction number sense. Alex needed to run only a mile, will completing the training in two segments satisfy this requirement? Yes, it will. Especially when Alex ran 1/2 mile to his friend's house and 5/8 mile to his grandma's house. There are two ways to solve this problem and both are explained on the commentary pages. The activity would be either a great lead-in to working with fractions, or a quick check-in for understanding. 

Common Core

5.NF.A.1 MP2 MP8