This is 2nd time blogging about this problem. 1st time-around post is here.
|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?|
|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)