This is a set of 20 problem solving task cards that present two different prices at different stores for products. Students must use proportional reasoning/unit rate to calculate which is the better buy. The earlier task cards in the set all work out to whole number (or whole cent) prices. A few of the cards give them students decimal answers that must be rounded to find the unit price. Many of these problems can be "scaled up" to a common multiple or "scaled down" to a price for one object and compared.
I created these cards to use with above level fifth graders who are learning how to use proportions but do not yet know the "cross multiply" method of solving a proportion. I also wanted the flexibility of having the kids find a unit price, or find another comparable price for a larger quantity. To that end, I created 2 sets of recording sheets. On one, kids simply need to circle the better buy. On the second, they must complete a proportion to find the cost for 1 item at each store.
My kids really loved doing these. I used the proportion recording sheets and ended up using 10 cards the first day and the other ten another day. They took kids a fair amount of time to solve (I did not give them calculators) and they really liked guessing which store would have the best deal. I made several sets of the cards and had them work with a partner, although each kid had a separate recording sheet.
These cards match Common Core 6.RP.3b, and would also support the comparable domain in Common Core 7.
This is an 11-page PDF file. Five pages are task cards (4 per page for a total of 20 cards). There is one option for a recording sheet that is one page (circle the answer), with a 1-page answer key. There is a second option for solving 2 proportions per task card, which is a 2-page recording sheet. The 2-page answer key is also included to match that format.