Fifth Grade Math: Relating Division and Fractions

Fifth graders began their fraction unit with a problem that linked division to fractions.  They solved a problem where they compared the prices of cat food at 2 stores.  Maria’s store sold 20 cans of cat food for $23, while Bob’s store sold 12 cans for $15.  There was such a variety of strategies in the fifth grade!  Many students used division to find the unit rate.  This makes sense since we just finished our decimal unit.  Others, however, thought about using a ratio table or multiplication to find a common number of cans.  If we know the price for the same number of cans, we can see which is the better buy.  Still others used reasoning to think about how a difference of $3 distributed among more cans would mean less per can.  Take a look at some of their work.

This week and next, we will continue with investigations related to the pet stores.  Through these problems, we will be continuing to look at ratio, an important idea that will occur more formally in sixth grade.