Tuesday, June 24, 2014

Multiplication and Estimating with Cuisenaire Rods

We built houses with Cuisenaire Rods and then estimated and calculated how many units were used in each structure.

Cuisenaire Rods come in 10 different colors. The white blocks are 1 cm cubes. The remaining rods are each 1 cm longer than the previous.

1 cm = white
2 cm = red
3 cm = green
4 cm = purple
5 cm = yellow
6 cm = blue-green
7 cm = black
8 cm = brown
9 cm = blue
10 cm = orange

First we built the square shown above and estimated how many cubic centimeters were used. The answer is 100 cubic cm.

Next unique structures were built. Each child had a turn to estimate the total number of cubic cm used in the structure. Then we used multiplication and addition to calculate the total volume.

For the structure above the math was done as follows:
orange - 10 rods used x 10 cm^3 per rod = 100 cm^3
brown - 8 rods used x 8 cm^3 per rod = 64 cm^3
blue-green - 6 rods used x 6 cm^3 per rod = 36 cm^3
purple - 4 rods used x 4 cm^3 per rod = 16 cm^3
green - 2 rods used x 3 cm^3 per rod = 6 cm^3
white - 1 rods used x 1 cm^3 per rod = 1 cm^3

Next the totals were added together: 100 + 64 + 36 + 16 + 6 + 1 = 223 cm^3

Finally we used comparison (subtraction) to determine who had the closest estimate.

The process was repeated with a few more structures.

When it was my son's turn, he knocked down his tower and lined up his rods to make determining the total volume of material used easier.

To see more of our hands on math activities please visit our Math Page.


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