How much IS a kilogram????

So today, we moved from simple grams to an actual kilo-gram.  This is one of my favorite FOSS lessons because it is actually building a kilogram unit using rocks!  The students will work as a team to create 10 bags with 100 grams of rocks in each bag.  I have five science groups, therefore each team is responsible for creating two bags filled with 100 grams of rocks.


As each team filled the bags with rocks, they were able to put gram stackers on the other side of the balance scale to equal 100 grams.  The kids really enjoyed this because they had to be precise in their measurements.

Next, we put all ten bags together into one gallon sized bag. I also had a kilogram weight that we passed around so that the kids could feel the weight of a kg vs. the weight of a gram.

It was a good connection to count each bag by 100's until we had all 10 bags which equaled 1,000.   I think having this visual model is important because mass is one of those units that can be hard to visualize - you can't see it like linear or even capacity; you have to feel it.