I can't remember where I found the problem, but it went something like this:
Bredan and Katie are playing Monopoly. At the end of the game Bredan has $120 more than Katie. Together they have $840. How much did each child have?
WELL, I could tell it was giving the kids a real challenge and I encouraged them to use strategies we've used throughout the year. After about 15 minutes I asked them to hand in their papers and let them know we'd take a deeper look.
When I looked through the solutions and the array of answers, I decided we needed to spend more time thinking on this concept. I put together a chart of the answers. On this page I also put down the basic facts from the problem; a total of $840 and Bredan had $120 more than Katie. I have 19 kids in my class, so only a few had the same answer and some didn't even have one yet.
These are the answers the class came up with on the first day. |
During lunch, I looked over their work and recorded their decisions on the chart from the morning. When we had a bit of time in the afternoon we looked over the work and tried to prove each of the answers. It's fascinating to hear what they are thinking. Most of the answers now totaled up to $840 but the method to get to a $120 difference was baffling to many of the kiddos. Some of the kids split the money up equally and took $120 from Katie and gave it to Bredan. They didn't understand that now Bredan has $240 more than Katie.
Earlier this year they got confused by a problem with equal groups and changing to a group that had 2 more than the other.
There are 4 kids in each group. If you need to change the groups so there are 2 more in one of the groups, how would you do it?