Feb 6, 2011

Mystery Bags

I've had quite a few requests for information about my Mystery Bag activity. I use Mystery Bags differently than what people might think to use them as. I place an amount of blocks (usually Unifex Cubes) inside of them. You can use a paper bag or Ziploc bag. This year my mom (THANK YOU!) volunteered to make me bags out of fabric. 
I used paper bags for a number of years. 

Let's say I wanted to help the students build an understanding of the number 36 (which is the number I use at the beginning of the year). I would put 36 blocks in each bag. Every student would receive a bag. I would use 2 colors of blocks and place them in fives. I put them in 5's because I am trying to get them out of counting by one's. Counting by one's is not mathematical thinking. 
The kids estimate how many blocks are in their bag, why they think this. From here they pull out he the blocks and combine the blocks together to come up with the amount. I watch to see what behaviours I'm seeing. Are they counting in chunks? Singles? How do they arrange the blocks? Do they make tens? And many more. 
In their math journals I have them represent the different ways to show their number. Some answers might include:
30 + 7
30 + 7 = 37
10 + 10 + 10 + 7 = 37 
thirty seven
a picture
37 = 7 + 30
40 - 3 = 37
Various other ways as well
There are a lot of different ways to use this activity to help build number sense. I will put the same number in everyone's bag for awhile. I also put the different number sequences. Here's a picture of what this looks like. 

Each student had a bag with a number in it. 
I put a number in half the bags and a different number in the other half. I have the students find someone who has a different number. They then compare the two numbers and find the difference between the two. When they compare the two numbers, students are building ideas towards adding to subtract and other significant strategies.
I use Mystery Bags all year to help my students build number, explain, represent and compare numbers. Kids build number and take them apart.
This student has shown how flexible he can be in his thinking.
 I will add more ideas for Mystery Bags in the coming days and weeks. If you have any questions please ask.

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