Monday, July 5, 2010

Measurement: Cubic Cm to mL

I don't remember how it came up, but one year I was talking with my students about cubic centimeters and how one cubic centimeter is the same as one milliliter.  It's not a concept my students use a lot, but a good one for them to start grasping.  Here's an activity to help them understand: 

Have students determine the volume of a centimeter cube* by measuring its length, width, and height and multiplying.  If done accurately, each of the dimensions should measure 1 cm, which gives a volume of 1 cm3.

Then have them determine the volume by water displacement.  If done accurately, it should have a volume of 1 mL.

There you have it - the same object has a volume of 1 cm3 and 1 mL - they are equivalent units.

*Ask the math and elementary teachers you know - they may have some centimeter cubes you can borrow (or even have) - you only need a few. 

You can then take it a step further... break out some other small blocks (this is a little hard... they have to be small enough to fit in a graduated cylinder).  Have students measure those in cm to determine volume.  Then have them determine volume by water displacement.

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