I've been trying to figure out how to make weighted cylinders for a while, and I finally made a few. I recently started buying yogurt smoothies for O, and I realized the containers would be perfect for this. I hate buying individually packaged snacks, so this made me feel better about it :)
To make the weighted cylinders, I filled them with plaster of paris. The first pair have 1 tablespoon of plaster of paris (mixed with 2 tablespoons of water), and the 2nd pair of cylinders has 2 tablespoons of plaster of paris (mixed with 4 tablespoons of water). I glued red and blue cardstock circles to the top of the bottles.
To match the cylinders, you pick up one bottle and feel the weight of it. Then pick up a second to see if they match. (You match a blue topped bottle with a red topped bottle). I was surprised by how difficult this work is. There are stickers on the bottoms of the cylinders for self-checking.
I plan to make a few more pairs when I have more bottles. I'm not sure if the plaster of paris is the best material to use for making these cylinders, but it works for now. This activity was simple to put together and fun to do!