This is a lab I developed to help my students understand the law of conservation of matter (mass). I found that students struggle understanding that while mass is conserved volume is not. In this lab the students will find the mass of a beaker covered with foil containing popcorn and oil. They will then pop the popcorn and find the mass after. They will then compare the mass before and after popping, as well as comparing the volume before and after. I have found that this helps the students gain common knowledge to which we can refer back to later.