# Coffees & Muffins #MFM2P #PBL

Scenario:

 What do you notice (facts)? What do you wonder (questions)? different prices why are they buying these Adding 3 extra coffees cost more by a little How much with it cost for 4 coffees and 4 muffins ? why is the kid buying coffee? whys the kid buying coffee? The totals are different on each side. One side has less drinks. How much is each item? nothing 2 different cost How much the cupcake cost each one How much the coffee cost each one there’s money, drinks, cupcakes how much each coffee and cupcake is For the first indivdual, it costs \$8.85 for three cupcakes and three coffee cups. For the second person, it costs \$5.35 for three cupcakes and one cup of coffee. Im curious about what brand of coffee that they are buying. It seems potentially no name or even something like a corner store kinda coffee. ew. oh yeah also how much do they each cost? The total cost are different How much it cost in each item I notice cupcakes , coffee , a boy and a girl how much is each The person on the left has more coffee and is going to spend more What is the individual price of the coffee and the muffins – They both ordered 3 muffins, but one had 3 cups of a drink and the other ordered one. – The one that ordered 3 cups, have to pay more. – How much does one drink cost? – How much does one muffin cost? – Does the person on the right have a better deal than the person on the left? Different prices and different subjects How much does it cost for each item Adding 3 more cups of of coffee is a little bit more than getting one cup of coffee how much is one cup of coffee Different objects in both pictures Why did the person on the left buy more diffent how much money does it cost to for one cup of coffee and one muffin

Solve for the cost of 1 muffin as well for the cost of 1 coffee (red/orange annotations are mine during whole class discussion):

They all solved it by subtracting what was common to both orders & splitting the remaining cost amongst the remaining coffees. The follow up questions on Pear Deck asked them to create an equation for each order. I then did some direct teaching on the side showing them how to do elimination using 2 different equations. Then I asked them to go to their board and use elimination to solve this problem. They started this on day 1 above but we class ended & we hadn’t finished. So on day 2, with a new group of partners & fresh boards, I sent them up to use elimination to solve fully:

We compared the solutions of the different groups and picked out the one board that had the most correct formatting of an algebraic solution. I drew parallels between their work during elimination and their earlier logic, pointing out how they are both eliminating something (I explained this more in depth & more eloquently).

We then did a quick check with Desmos:

The individual practice to wrap up was a Khan Academy exercise set on elimination not involving any multiplication of equations.

Activity available here.

– Laura Wheeler (Teacher @ Ridgemont High School, OCDSB; Ottawa, ON)