Don't you just love it when you hear someone speak and it changes your life?
Dan Meyer's recent TED had this effect on me and my maths teaching and long may it last...
As you can see, this is largely set in the secondary school context, but we in primary school can figure this out ... surely.
So here is my first attempt at it. I started this last Monday.
My maths class had been working on addition and subtraction strategies for 3 digit numbers. Specifically, we were working on place value strategy and compensation (also known as equal addition).
I was browsing through the numeracy project resources (www.nzmaths.co.nz) and thumbing through a numeracy project based textbook and I just couldn't go through with it. I looked at the questions and wondered how I could "DD MYERS" them and none stood out as even slightly inspirational.
I tweeted a pretty indirect cry for help but nothing happened. I googled "DD Myers primary school context" nothing much. I racked my brain, went to bed, gave up...
Then at 3am I woke up chanting "money money money money money MUUUUNay" (you know the one).
That morning at 7am I was parked outside the local supermarket waiting for it to open. I went to the trolley park where they keep stacks of promotional mailures and carefully counted out a class set of them. (incidentally a bolshy checkout chick called security on me and I had to go to another supermarket but that's another story!)
Anyway, 2 hours later, they were looking at me and I was looking at them.
I explained to them that they would be using the fliers for maths for the day.
Then came the ambiguous statement...
"YOU ARE TO GO THROUGH THE FLIER AND PURCHASE ENOUGH GROCERIES TO FEED YOUR FAMILY FOR THREE DAYS"
Then they started to generate the questions, the rules, the formulas
"How much money can we spend? I have more people in my family, do I get more money? Do we have to buy breakfast? Can we buy anything we like?
Together we narrowed it down to a budget of $120, they had to buy breakfast, lunch, dinner and snacks. The lunch had to be suitable for school lunches.
Within minutes they discovered that the mailer did not have milk, so we went online and found the woolworths online shopping page where they list the prices for most grocery items (enter your nearest suburb and away you go).
By the time they were really getting into it, it was the end of the maths session. The time flew by!
The next day I made up a sheet outlining the success criteria and blank lines for them to write a list of all the food items they would need.
I asked them "If a kilo on mince costs $7.99, how much would 1/2 a kilo cost?
It would cost $4.00, Litia relplied.
"And how do you know that?"
"Well $7.99 is really $8 and half of 8 is 4"
Interestingly if I had asked her what 8 DIVIDED by 4 was she would look at me blankly. The previous week when I was asking them to round up number like 799 (for compensation purposes) they really struggled with that concept.
Then, like magic, the genuine question came out ...
How can we add these up without a calculator?
I SEIZED THE MOMENT
"If you needed to add $7.99 for a kilo of mince and $2.30 for a packet of pasta how could you do this using the compensation strategy?"
We'll add 1 cent to the $7.99 to make it $8 and then 'steal' 1 cent from the $2.30 making it $2.29
$7.99 + $2.30 is the same as
$8.00 + $2.29 (COMPENSATION STRATEGY)
How many cents do we have? (PLACE VALUE STRATEGY)
How many dollars do we have?
10So the answer is ... $10.29
Then we started adding bigger lists of numbers ... For fun!
Then it was time for the session to end ... again. Again time flew...
The next day a child came into the class with a countdown mailer tucked under her arm and asked if I could show her again the way to add the numbers up!
So as a warm-up I ask the kids to find the prices and then add some random items using the place value and and compensation strategies. Not only did they do this enthusiastically but they actually knew what I was asking them to do.
I was out of the classroom for the next two days so it will be interesting to see if they have completed their original mission (Of feeding their families for three days) most of them were fairly close by the end of Wednesday.
What I found even more compelling about this series of lessons was the incidental learning along the way and the meaningful conversations also.
"is it appropriate to feed your entire family a bag of oven fries for dinner? Those bags are only 500gms How many fries do you think that would be each"
"Would you normally have a king-size block of chocolate for breakfast?"
"How many loaves of bread would you have to buy to make sandwiches for 4 kids?"
"How many sandwiches do you have in your school lunch, how many kids in your family? How many slices of bread is that?"
The greatest part was that the kids were genuinely asking the questions and genuinely wanting to know how to add things together.