Miss Ashley wants to buy a new heater because her house is really cold in winter. She looks up the specials at different shops and tries to buy the cheapest heater she can find. The Warehouse have a heater that is $69.99 but it is on sale for 30% off. Kmart has a heater for $45.00, but it is only 10% off. Which heater cheaper and by how much?
We selected one group to present the 'first part' of their solution, which was finding 10% of $45. All the groups did this first, as 10% is easier to find than 30%.
Their explanation started off well, but one group member wrote something that wasn't on the group paper and the rest of the group didn't know what to say about or how to explain it. We had to help out a little bit so help them explain that 10% of $45 is $4.50.
We were running out of time, so instead of a second group presenting the 'other part', I got up and facilitated it with the group. The way I wrote out the 3 lots of 10% (therefore 3 lots of 6.99) helped the students to understand where the 30% went.
Again we restated the key idea in the same written way to help them connect between the two parts.
Together we worked out what 20% would be, as a way of practising the skill we had just learnt (adding 10%'s together until you get to 20 or 30%)
To challenge the children who really understood it, I made up another heater situation that was $84.99 at Bunnings but it was 40% off. And the students helped me to solve (i.e. they said it out loud, all I did was write it down). In the end we compared the three prices and were able to find out which heater was cheaper.
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