This Better Lesson resource contains a 5E model investigation on the Law of Conservation of Mass. The lesson begins with a discussion of the Carl Sagan quote: “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff” and drawing an analogy to a slice of onion and our universe. The lesson continues with a lab in which students use glow sticks and popsicles to investigate the mass of reactants and products before and after both physical and chemical changes in a closed system. Students then plan their own investigation on the conservation of mass using baking soda and vinegar.