This is a fun activity I tend to do in the spring time around Easter (when I generally teach the Periodic Table). This lab is great for getting practice with balances in, as well as having the students critically think about the Periodic Table.
I put coins or candy in the Easter Eggs so that they have fairly different masses. As it states in the directions, I do not try to make it so they match the actual masses of an element. I just want the students to accurately rank the eggs, and compare them to the ranked elements.
This activity helps to familiarize the students with the Periodic Table, while still allowing them to have fun. I use this with 8th grade.